fix(ui): seed QRs use the SeedQR standard so hardware wallets can scan them

Plain-text seed QRs didn't scan into Passport Prime — wallets that
import seeds by QR (Passport, SeedSigner, Keystone, Nunchuk, Sparrow)
expect the SeedQR standard: each BIP39 word as its zero-padded 4-digit
wordlist index, concatenated into a numeric QR.

- new utils/seedqr.ts encodes BIP39 words per the SeedSigner spec
  (@scure/bip39 wordlist; vector-checked abandon=0000, zoo=2047)
- new shared SeedRevealPanel (Words/QR tabs, tap-to-reveal blur) now
  backs the LND reveal AND the Settings→Backup recovery-phrase reveal,
  so every current and future seed reveal behaves the same
- onboarding seed + Settings reveal: QR defaults to SeedQR with a
  plain-text toggle
- LND seed stays plain-text-only with an explicit note: aezeed is not
  BIP39 and only restores into LND-based wallets (Zeus/Blixt/another
  node) — SeedQR-encoding it would just mislead

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/views/settings/BackupSection.vue

@@ -2,6 +2,7 @@
 import { ref } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { rpcClient } from '@/api/rpc-client'
+import SeedRevealPanel from '@/components/SeedRevealPanel.vue'
 
 const { t } = useI18n()
 
@@ -329,20 +330,7 @@ defineExpose({ loadBackups })
         </template>
 
         <template v-else>
-          <p class="text-sm text-white/60 mb-3">Write these down and store them offline. Tap to {{ wordsHidden ? 'reveal' : 'hide' }}.</p>
-          <div class="relative">
-            <div
-              class="grid grid-cols-2 sm:grid-cols-3 gap-2 p-3 bg-white/5 rounded-lg transition-all select-text"
-              :class="wordsHidden ? 'blur-md' : ''"
-              @click="wordsHidden = !wordsHidden"
-            >
-              <div v-for="(w, i) in revealedWords" :key="i" class="flex items-center gap-1.5 text-sm">
-                <span class="text-white/30 text-xs w-5 text-right">{{ i + 1 }}.</span>
-                <span class="text-white font-mono">{{ w }}</span>
-              </div>
-            </div>
-            <button v-if="wordsHidden" type="button" class="absolute inset-0 flex items-center justify-center text-xs text-white/70 font-medium" @click="wordsHidden = false">Tap to reveal</button>
-          </div>
+          <SeedRevealPanel :words="revealedWords" />
           <div class="flex gap-2 pt-4">
             <button type="button" @click="copyRevealedWords" class="flex-1 glass-button rounded-lg px-4 py-2 text-sm font-medium">{{ wordsCopied ? 'Copied!' : 'Copy' }}</button>
             <button type="button" @click="closeReveal" class="flex-1 glass-button rounded-lg px-4 py-2 text-sm font-medium bg-orange-500/20 border-orange-400/30">Done</button>