fix: bitcoin receive, AIUI pointer input, electrs self-heal, OTA timeout

- LND wallet: request correct address type so receive-address generation
  no longer 400s
- AIUI/app session: on-screen pointer can click + type into app content
  (incl. app store search); "open in new tab" opens the phone browser;
  mobile credential modal centered instead of full-height
  (remote-relay.ts, AppSession.vue, AppSessionFrame.vue, AppIconGrid.vue,
  openExternal.ts, WebViewScreen.kt) + remote-relay tests
- health_monitor: electrs auto-recovers from a corrupt index and shows a
  percent/block-height progress screen while reindexing (useElectrsSync.ts)
- update.rs: drop retired tx1138 secondary mirror (one-time migration);
  longer download timeout for slow connections
- CHANGELOG: v1.7.90-alpha notes
- tests/release/run.sh: harness tweaks

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neode-ui/src/views/appSession/AppSessionFrame.vue

@@ -9,8 +9,40 @@
       </div>
     </Transition>
 
+    <!-- ElectrumX sync screen — shown before the real UI while the on-chain
+         index is still being built (the Electrum server can't serve clients
+         until then). Mirrors the Fedimint Guardian "wait page" design. -->
+    <Transition name="content-fade">
+      <div v-if="electrsSync" class="absolute inset-0 z-10 flex flex-col items-center justify-center">
+        <div class="text-center px-8 w-full max-w-md">
+          <div class="w-16 h-16 mx-auto mb-4 rounded-2xl bg-white/5 border border-white/10 flex items-center justify-center">
+            <svg class="w-8 h-8 text-orange-300 animate-pulse" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path stroke-linecap="round" stroke-linejoin="round" stroke-width="1.5" d="M4 7v10a2 2 0 002 2h12a2 2 0 002-2V7M4 7l8 5 8-5M4 7l8-4 8 4" />
+            </svg>
+          </div>
+          <h3 class="text-lg font-semibold text-white mb-2">{{ appTitle }} is syncing</h3>
+          <p class="text-white/50 text-sm mb-5">
+            ElectrumX is building its index from the blockchain. The UI opens
+            automatically once it's ready — you can keep using the rest of Archipelago.
+          </p>
+          <div class="w-full h-2 rounded-full bg-white/10 overflow-hidden mb-2">
+            <div
+              class="h-full bg-orange-400/80 transition-all duration-700"
+              :style="{ width: `${Math.min(100, Math.max(2, electrsSync.progress_pct)).toFixed(1)}%` }"
+            ></div>
+          </div>
+          <p class="text-white/70 text-sm font-medium mb-1">{{ electrsSync.progress_pct.toFixed(1) }}%</p>
+          <p class="text-white/40 text-xs">
+            Block {{ electrsSync.indexed_height.toLocaleString() }} of {{ electrsSync.network_height.toLocaleString() }}
+            <template v-if="electrsSync.index_size"> · {{ electrsSync.index_size }} indexed</template>
+          </p>
+          <p v-if="electrsSync.stale" class="text-yellow-400/70 text-xs mt-2">Reconnecting to ElectrumX…</p>
+        </div>
+      </div>
+    </Transition>
+
     <div
-      v-if="appUrl && !iframeBlocked"
+      v-if="appUrl && !iframeBlocked && !electrsSync"
       class="absolute inset-0 app-session-frame-scroll-host"
       tabindex="-1"
       @pointerdown="focusIframe"
@@ -79,6 +111,7 @@
 
 <script setup lang="ts">
 import { nextTick, ref, watch } from 'vue'
+import type { ElectrsSyncStatus } from '@/composables/useElectrsSync'
 
 const props = defineProps<{
   appUrl: string
@@ -91,6 +124,9 @@ const props = defineProps<{
   refreshKey: number
   blockedReason?: string
   blockedTitle?: string
+  // Non-null only for ElectrumX while its index is still building — shows the
+  // sync screen and gates the iframe until status flips to "synced".
+  electrsSync?: ElectrsSyncStatus | null
 }>()
 
 const emit = defineEmits<{