feat: BIP-39 master seed for unified key derivation

Replace fragmented random key generation with a single 24-word BIP-39
mnemonic that deterministically derives all node keys: Ed25519 (DID),
secp256k1 (Nostr/Bitcoin), BIP-84 xprv (Bitcoin Core), and LND aezeed
entropy. New onboarding flow: seed generate → word verification → identity
naming. Restore path enabled via 24-word entry. Includes seed RPC handlers,
mock backend support, LND/Bitcoin Core wallet-from-seed integration, and
UI polish across settings and discover views.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

neode-ui/src/views/OnboardingIntro.vue

@@ -29,40 +29,11 @@
           tabindex="0"
           role="button"
           class="text-white/50 hover:text-white/80 underline text-sm cursor-pointer mt-4 block text-center onb-cta"
-          @click="showRestore = true"
-          @keydown.enter="showRestore = true"
+          @click="goToRestore"
+          @keydown.enter="goToRestore"
         >
-          Restore from backup
+          Restore from seed phrase
         </a>
-
-        <!-- Restore Panel -->
-        <div v-if="showRestore" class="mt-6 glass-card px-6 py-6 text-left">
-          <h3 class="text-sm font-semibold text-white/80 mb-3 uppercase tracking-wide">Restore Identity from Backup</h3>
-          <input
-            type="file"
-            accept=".json"
-            class="block w-full text-sm text-white/60 file:mr-4 file:py-2 file:px-4 file:rounded file:border-0 file:text-sm file:bg-white/10 file:text-white/80 hover:file:bg-white/20 mb-3"
-            @change="onFileSelect"
-          />
-          <input
-            v-model="passphrase"
-            type="password"
-            placeholder="Backup passphrase"
-            class="w-full px-4 py-2 bg-white/10 border border-white/20 rounded-lg text-white text-sm focus:outline-none focus:border-white/40 mb-3"
-          />
-          <p v-if="restoreError" class="text-red-400 text-xs mb-2">{{ restoreError }}</p>
-          <p v-if="restoreSuccess" class="text-green-400 text-xs mb-2">Identity restored successfully!</p>
-          <div class="flex gap-3">
-            <button class="glass-button text-sm px-4 py-2" @click="showRestore = false">Cancel</button>
-            <button
-              class="glass-button text-sm px-4 py-2"
-              :disabled="!restoreFile || !passphrase || restoreLoading"
-              @click="performRestore"
-            >
-              {{ restoreLoading ? 'Restoring...' : 'Restore' }}
-            </button>
-          </div>
-        </div>
       </div>
     </div>
   </div>
@@ -72,7 +43,6 @@
 import { ref, onMounted } from 'vue'
 import { useRouter } from 'vue-router'
 import AnimatedLogo from '@/components/AnimatedLogo.vue'
-import { rpcClient } from '@/api/rpc-client'
 import { playNavSound } from '@/composables/useNavSounds'
 
 const router = useRouter()
@@ -90,49 +60,9 @@ function goToOptions() {
   router.push('/onboarding/path').catch(() => {})
 }
 
-// Restore from backup
-const showRestore = ref(false)
-const restoreFile = ref<Record<string, unknown> | null>(null)
-const passphrase = ref('')
-const restoreLoading = ref(false)
-const restoreError = ref('')
-const restoreSuccess = ref(false)
-
-function onFileSelect(e: Event) {
-  const target = e.target as HTMLInputElement
-  const file = target.files?.[0]
-  if (!file) return
-  const reader = new FileReader()
-  reader.onload = () => {
-    try {
-      restoreFile.value = JSON.parse(reader.result as string)
-      restoreError.value = ''
-    } catch {
-      restoreError.value = 'Invalid backup file format'
-      restoreFile.value = null
-    }
-  }
-  reader.readAsText(file)
-}
-
-async function performRestore() {
-  if (!restoreFile.value || !passphrase.value) return
-  restoreLoading.value = true
-  restoreError.value = ''
-  try {
-    await rpcClient.call({
-      method: 'backup.restore-identity',
-      params: { backup: restoreFile.value, passphrase: passphrase.value },
-    })
-    restoreSuccess.value = true
-    setTimeout(() => {
-      router.push('/onboarding/did')
-    }, 1500)
-  } catch (err) {
-    restoreError.value = err instanceof Error ? err.message : 'Restore failed'
-  } finally {
-    restoreLoading.value = false
-  }
+function goToRestore() {
+  playNavSound('action')
+  router.push('/onboarding/seed-restore').catch(() => {})
 }
 </script>