fix(wallet): channel modals above settings modal, tx rail filters, LND seed-backup prompt

- Open/Close Channel modals sat at z-[60], BEHIND the wallet settings
  BaseModal (z-3000) — clicking 'Open Channel' looked like nothing
  happened while the form changed in the background. Raised to z-3100.
- TransactionsModal gains rail filter chips (All / On-chain / Lightning
  / Ecash with counts): instant ecash micro-payments were burying the
  standard transactions.
- Global LND seed-backup banner: once the wallet exists and the seed is
  un-acknowledged, a dismissible glass banner (24h snooze) prompts and
  routes to the LND backup card; polls only when authenticated, stops
  permanently once acked.

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

neode-ui/src/App.vue

@@ -40,6 +40,9 @@
     <!-- Global "mesh device detected" setup flow (fires on any page) -->
     <MeshDeviceSetupModal />
 
+    <!-- Nudge to back up the Lightning seed once a wallet exists (any page) -->
+    <LndSeedBackupPrompt />
+
     <!-- Global persistent audio player (bottom bar) -->
     <GlobalAudioPlayer />
 
@@ -92,6 +95,7 @@ import Screensaver from './components/Screensaver.vue'
 import HelpGuideModal from './components/HelpGuideModal.vue'
 import GlobalAudioPlayer from './components/GlobalAudioPlayer.vue'
 import MeshDeviceSetupModal from './components/mesh/MeshDeviceSetupModal.vue'
+import LndSeedBackupPrompt from './components/LndSeedBackupPrompt.vue'
 import { useMeshStore } from './stores/mesh'
 
 import { useControllerNav } from '@/composables/useControllerNav'