feat: factory reset, backup restore, auto-identity creation

- system.factory-reset RPC: wipes user data, preserves images/node_key
- Factory Reset button in Settings with confirmation modal
- backup.restore-identity RPC: decrypts and restores DID key
- Restore from Backup panel in OnboardingIntro first screen
- Auto-create default identity with Nostr key on boot if none exist

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

neode-ui/src/views/Settings.vue

@@ -818,6 +818,42 @@
         </button>
       </div>
     </div>
+
+    <!-- Factory Reset Section -->
+    <div class="path-option-card px-6 py-6 mt-6 border-red-500/30">
+      <h2 class="text-xl font-semibold text-red-400/90 mb-3">Factory Reset</h2>
+      <p class="text-sm text-white/60 mb-4">
+        Wipe all user data, identities, and credentials. Container images are preserved. The node will restart and show the onboarding screen.
+      </p>
+      <button
+        class="glass-button text-red-400 border-red-500/30 hover:border-red-500/50"
+        @click="showFactoryResetConfirm = true"
+      >
+        Factory Reset
+      </button>
+    </div>
+
+    <!-- Factory Reset Confirmation Modal -->
+    <Teleport to="body">
+      <div v-if="showFactoryResetConfirm" class="fixed inset-0 z-50 flex items-center justify-center bg-black/60 backdrop-blur-sm">
+        <div class="glass-card px-8 py-8 max-w-md mx-4">
+          <h3 class="text-lg font-semibold text-white/90 mb-3">Are you sure?</h3>
+          <p class="text-sm text-white/60 mb-6">
+            This will delete all identities, credentials, and settings. This cannot be undone.
+          </p>
+          <div class="flex gap-3 justify-end">
+            <button class="glass-button" @click="showFactoryResetConfirm = false">Cancel</button>
+            <button
+              class="glass-button text-red-400 border-red-500/30"
+              :disabled="factoryResetLoading"
+              @click="performFactoryReset"
+            >
+              {{ factoryResetLoading ? 'Resetting...' : 'Yes, Reset' }}
+            </button>
+          </div>
+        </div>
+      </div>
+    </Teleport>
   </div>
 </template>
 
@@ -837,6 +873,24 @@ import type { UIMode } from '@/types/api'
 const router = useRouter()
 const { t, locale } = useI18n()
 const store = useAppStore()
+
+// Factory Reset
+const showFactoryResetConfirm = ref(false)
+const factoryResetLoading = ref(false)
+async function performFactoryReset() {
+  factoryResetLoading.value = true
+  try {
+    await rpcClient.call({ method: 'system.factory-reset', params: { confirm: true } })
+    localStorage.clear()
+    showFactoryResetConfirm.value = false
+    router.push('/onboarding/intro')
+  } catch (err) {
+    // Service likely restarted — redirect anyway
+    localStorage.clear()
+    showFactoryResetConfirm.value = false
+    router.push('/onboarding/intro')
+  }
+}
 const supportedLocales = SUPPORTED_LOCALES
 const currentLocale = computed(() => locale.value)
 async function changeLocale(code: string) {