feat(ui): dual-ecash wallet settings, buy-peer-files, seed backup, assorted fixes

- Tabbed Wallet Settings modal (Cashu + Fedimint) and dual-balance wallet card
- Buy a peer's paid file (ecash / node Lightning / on-chain / external QR)
- Recovery-phrase reveal + backup section; onboarding seed retry resilience
- NetBird HTTPS launch, remote-control two-finger scroll + external-open
- Shared BackButton, single-v version label, mesh Bitcoin header toggles

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

neode-ui/src/views/web5/Web5NetworkingProfitsSettings.vue

@@ -3,6 +3,7 @@ import { computed, onMounted, ref } from 'vue'
 import { useRouter } from 'vue-router'
 import { rpcClient } from '@/api/rpc-client'
 import ToggleSwitch from '@/components/ToggleSwitch.vue'
+import BackButton from '@/components/BackButton.vue'
 
 const router = useRouter()
 
@@ -117,11 +118,7 @@ onMounted(load)
 
 <template>
   <div class="pb-6">
-    <button
-      type="button"
-      class="text-xs px-3 py-1.5 mb-4 rounded-md bg-white/5 hover:bg-white/10 text-white/70 hover:text-white transition-colors"
-      @click="router.push('/dashboard/web5')"
-    >← Back to Web5</button>
+    <BackButton label="Back to Web5" @click="router.push('/dashboard/web5')" />
 
     <div class="mb-6">
       <h1 class="text-3xl font-bold text-white mb-2">Networking Profits — Settings</h1>