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/components/LightningChannelsPanel.vue

@@ -135,7 +135,7 @@
 
     <!-- Open Channel Modal -->
     <Teleport to="body">
-    <div v-if="showOpenModal" class="fixed inset-0 z-[60] flex items-center justify-center bg-black/60 backdrop-blur-md" @click.self="showOpenModal = false">
+    <div v-if="showOpenModal" class="fixed inset-0 z-[3100] flex items-center justify-center bg-black/60 backdrop-blur-md" @click.self="showOpenModal = false">
       <div class="glass-card p-6 w-full max-w-md mx-4 max-h-[90vh] overflow-y-auto">
         <h2 class="text-lg font-bold text-white mb-4">Open Channel</h2>
 
@@ -233,7 +233,7 @@
 
     <!-- Close Confirmation Modal -->
     <Teleport to="body">
-    <div v-if="closeTarget" class="fixed inset-0 z-[60] flex items-center justify-center bg-black/60 backdrop-blur-md" @click.self="closeTarget = null">
+    <div v-if="closeTarget" class="fixed inset-0 z-[3100] flex items-center justify-center bg-black/60 backdrop-blur-md" @click.self="closeTarget = null">
       <div class="glass-card p-6 w-full max-w-sm mx-4">
         <h2 class="text-lg font-bold text-white mb-2">Close Channel?</h2>
         <p class="text-white/60 text-sm mb-4">This will cooperatively close the channel with peer {{ closeTarget.remote_pubkey.slice(0, 16) }}...</p>