feat(ecash): import a backup phrase from another NUT-13 wallet

Bring-your-own, the open question the migration plan left. Point this
wallet at a phrase you already hold — Minibits, Nutstash, cdk-cli — and
its coins become restorable here, which is the other half of "these
words are portable".

Replacing an established phrase is the one genuinely lossy thing this
module can do, so it is treated that way. The coins already held stay
spendable: they are proofs, not derivations, and nothing here touches
`ecash.json`. But they were minted under the *old* phrase, so a restore
will no longer find them. Hence an explicit confirm, a prompt to reveal
and write down the current phrase first, and — most importantly — the
replaced phrase is archived beside the wallet, never overwritten. It may
be the last copy of the words a balance was minted under, and quietly
destroying that is precisely what this module exists to prevent.

Re-importing the phrase already in use is a no-op rather than a
replacement, so it archives nothing.

Counters are deliberately left alone. They are per-keyset and
seed-relative, so under a new seed they merely start high, which costs
nothing because a restore scans from zero regardless. Resetting them
would be the dangerous choice on the day someone imports the phrase they
were already using.

`imported` is its own provenance rather than reusing `independent`: both
mean the node's recovery phrase does not cover the wallet, but only one
of them means the operator already knows where else the words live.

15 NUT-13 tests green, 1000 frontend tests green.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

neode-ui/src/components/EcashSeedBackup.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { ref, onMounted } from 'vue'
+import { ref, computed, onMounted } from 'vue'
 import { rpcClient } from '@/api/rpc-client'
 import SeedRevealPanel from '@/components/SeedRevealPanel.vue'
 
@@ -20,7 +20,7 @@ import SeedRevealPanel from '@/components/SeedRevealPanel.vue'
 
 type SeedStatus = {
   active: boolean
-  source: 'node-seed' | 'independent' | null
+  source: 'node-seed' | 'independent' | 'imported' | null
   can_activate: boolean
   /** Whether a phrase can be *derived* from the node's recovery phrase. When
    *  false the wallet still gets a backup — it is just independent, and the
@@ -105,6 +105,60 @@ async function copyRevealedWords() {
   } catch { /* clipboard unavailable */ }
 }
 
+// ── Import ─────────────────────────────────────────────────────────────────
+// Bring-your-own: point this wallet at another NUT-13 wallet's derivation, so
+// coins held in Minibits, Nutstash or cdk-cli become restorable here.
+//
+// Replacing an established phrase is the one lossy thing on this screen. The
+// coins already held stay spendable — they are proofs, not derivations — but
+// they were minted under the old phrase, so a restore will no longer find
+// them. Hence the explicit confirmation, and the reminder to write the
+// current phrase down first.
+const showImportModal = ref(false)
+const importWords = ref('')
+const importPassword = ref('')
+const importCode = ref('')
+const importConfirm = ref(false)
+const importing = ref(false)
+const importError = ref('')
+const importDone = ref(false)
+
+const importWordCount = computed(
+  () => importWords.value.trim().split(/\s+/).filter(Boolean).length,
+)
+
+function openImport() {
+  importWords.value = ''
+  importPassword.value = ''
+  importCode.value = ''
+  importConfirm.value = false
+  importError.value = ''
+  importDone.value = false
+  showImportModal.value = true
+}
+
+async function submitImport() {
+  if (importing.value || !importPassword.value || importWordCount.value === 0) return
+  importing.value = true
+  importError.value = ''
+  try {
+    const params: Record<string, string | boolean> = {
+      words: importWords.value.trim(),
+      password: importPassword.value,
+      confirm: importConfirm.value,
+    }
+    if (importCode.value) params.code = importCode.value
+    await rpcClient.call({ method: 'wallet.ecash-seed-import', params })
+    importDone.value = true
+    importWords.value = ''
+    await loadStatus()
+  } catch (e: unknown) {
+    importError.value = e instanceof Error ? e.message : 'Import failed'
+  } finally {
+    importing.value = false
+  }
+}
+
 // ── Restore ────────────────────────────────────────────────────────────────
 // The other half of the backup. Safe to run against a working wallet: the
 // backend skips coins already held and never re-adds spent ones, so this is
@@ -182,10 +236,10 @@ async function restoreFromPhrase() {
           </template>
         </p>
 
-        <p v-if="status?.source === 'independent'" class="mt-2 text-xs text-orange-300/90">
+        <p v-if="status?.source === 'independent' || status?.source === 'imported'" class="mt-2 text-xs text-orange-300/90">
           This wallet's phrase was <strong>not</strong> derived from the node's recovery
-          phrase — restoring the node will not bring the ecash back. Write these words down
-          separately.
+          phrase{{ status?.source === 'imported' ? ' — it was imported' : '' }}, so restoring
+          the node will not bring the ecash back. Only these words will.
         </p>
 
       </div>
@@ -216,8 +270,87 @@ async function restoreFromPhrase() {
       <p v-if="restoreMsg" role="status" aria-live="polite" class="mt-3 text-xs alert-success px-3 py-2 rounded-lg">{{ restoreMsg }}</p>
       <p v-if="restoreError" role="alert" class="mt-3 text-xs alert-error px-3 py-2 rounded-lg">{{ restoreError }}</p>
     </div>
+
+    <div class="mt-4 pt-4 border-t border-white/10">
+      <div class="flex items-start justify-between gap-4">
+        <p class="text-sm text-white/60 min-w-0">
+          <span class="text-white/80 font-medium">Use a phrase from another wallet.</span>
+          Point this wallet at a phrase you already have — from Minibits, Nutstash or
+          <span class="font-mono">cdk-cli</span> — so its coins can be restored here.
+        </p>
+        <button
+          type="button"
+          class="shrink-0 glass-button rounded-lg px-4 py-2 text-sm font-medium"
+          @click="openImport"
+        >Import</button>
+      </div>
+    </div>
   </div>
 
+  <Teleport to="body">
+    <div
+      v-if="showImportModal"
+      class="fixed inset-0 z-[3000] flex items-center justify-center p-4 bg-black/60 backdrop-blur-md"
+      @click.self="showImportModal = false"
+    >
+      <div class="glass-card p-6 w-full max-w-md" role="dialog" aria-modal="true" aria-labelledby="import-ecash-seed-title">
+        <h3 id="import-ecash-seed-title" class="text-lg font-semibold text-white mb-1">Import an ecash phrase</h3>
+
+        <template v-if="importDone">
+          <p class="text-sm text-white/70 my-4">
+            Imported. This wallet now derives its coins from that phrase — run
+            <span class="text-white/90 font-medium">Restore</span> to pull in the coins it
+            owns at your mint.
+          </p>
+          <button type="button" @click="showImportModal = false" class="w-full glass-button rounded-lg px-4 py-2 text-sm font-medium bg-orange-500/20 border-orange-400/30">Done</button>
+        </template>
+
+        <template v-else>
+          <p class="text-sm text-white/60 mb-4">
+            Paste the 24-word phrase from the other wallet. The coins already in this wallet
+            stay spendable either way.
+          </p>
+          <form @submit.prevent="submitImport" class="space-y-3">
+            <div>
+              <label class="block text-xs text-white/60 mb-1">
+                Recovery phrase
+                <span class="text-white/30">({{ importWordCount }} word{{ importWordCount === 1 ? '' : 's' }})</span>
+              </label>
+              <textarea v-model="importWords" rows="3" spellcheck="false" autocapitalize="none" autocomplete="off" class="w-full px-3 py-2 rounded-lg bg-white/5 border border-white/10 text-white text-sm font-mono focus:outline-none focus:border-white/30" placeholder="abandon abandon abandon …"></textarea>
+            </div>
+            <div>
+              <label class="block text-xs text-white/60 mb-1">Password</label>
+              <input v-model="importPassword" type="password" autocomplete="current-password" class="w-full px-3 py-2 rounded-lg bg-white/5 border border-white/10 text-white text-sm focus:outline-none focus:border-white/30" placeholder="Your login password" />
+            </div>
+            <div>
+              <label class="block text-xs text-white/60 mb-1">2FA code <span class="text-white/30">(if enabled)</span></label>
+              <input v-model="importCode" inputmode="numeric" autocomplete="one-time-code" class="w-full px-3 py-2 rounded-lg bg-white/5 border border-white/10 text-white text-sm font-mono tracking-widest focus:outline-none focus:border-white/30" placeholder="123456" />
+            </div>
+
+            <label v-if="status?.active" class="flex items-start gap-2 text-xs text-orange-300/90 bg-orange-500/10 border border-orange-400/20 rounded-lg px-3 py-2">
+              <input type="checkbox" v-model="importConfirm" class="mt-0.5 shrink-0" />
+              <span>
+                Replace this wallet's current phrase. Coins minted under the old one stay
+                spendable but a restore will no longer find them — reveal and write the
+                current phrase down first. The old phrase is archived on the node, not deleted.
+              </span>
+            </label>
+
+            <p v-if="importError" role="alert" class="text-xs text-red-300 bg-red-500/10 border border-red-400/20 rounded-lg px-3 py-2">{{ importError }}</p>
+            <div class="flex gap-2 pt-1">
+              <button type="button" @click="showImportModal = false" class="flex-1 glass-button rounded-lg px-4 py-2 text-sm font-medium">Cancel</button>
+              <button
+                type="submit"
+                :disabled="importing || !importPassword || importWordCount === 0 || (status?.active && !importConfirm)"
+                class="flex-1 glass-button rounded-lg px-4 py-2 text-sm font-medium bg-orange-500/20 border-orange-400/30 disabled:opacity-50"
+              >{{ importing ? 'Importing…' : 'Import' }}</button>
+            </div>
+          </form>
+        </template>
+      </div>
+    </div>
+  </Teleport>
+
   <Teleport to="body">
     <div
       v-if="showRevealModal"