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/main.ts

@@ -4,6 +4,7 @@ import './style.css'
 import App from './App.vue'
 import router from './router'
 import i18n from './i18n'
+import { displayVersion } from '@/utils/version'
 
 // Clipboard polyfill for HTTP (non-secure) contexts where navigator.clipboard is unavailable
 if (!navigator.clipboard) {
@@ -31,6 +32,11 @@ app.use(pinia)
 app.use(router)
 app.use(i18n)
 
+// Global version formatter — normalizes version labels to a single "v" prefix
+// (some sources already carry one, which produced "vv1.2.3"). Use `$ver(x)` in
+// templates instead of hard-coding a `v` prefix.
+app.config.globalProperties.$ver = displayVersion
+
 app.config.errorHandler = (err, _instance, info) => {
   console.error('[Vue Error]', err, info)
   const { error } = useToast()