fix(ui): surface real error instead of generic toast + catch async errors

The global Vue errorHandler swallowed every crash into "Something went wrong.
Please refresh the page." — which hides exactly what we need to diagnose the
companion-app (Android WebView) post-login crash. Now:
- the toast shows the real (truncated) error message;
- a 25-entry ring buffer is kept on window.__archyErrors for retrieval where
  there's no console (companion WebView via chrome://inspect, or a debug view);
- window 'error' and 'unhandledrejection' listeners catch async/non-Vue errors
  that Vue's errorHandler misses (e.g. a JS API absent in an older WebView).

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

neode-ui/src/main.ts

@@ -37,10 +37,35 @@ app.use(i18n)
 // 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()
-  error('Something went wrong. Please refresh the page.')
+// Keep a small ring buffer of the most recent errors on `window.__archyErrors`
+// so a crash that only reproduces inside a specific runtime (e.g. the Android
+// companion WebView, where there's no easy console) can be retrieved after the
+// fact — read it from chrome://inspect, or we can surface it in a debug view.
+interface ArchyErrorEntry { when: string; source: string; message: string; info?: string; stack?: string }
+const errorLog: ArchyErrorEntry[] = []
+;(window as unknown as { __archyErrors?: ArchyErrorEntry[] }).__archyErrors = errorLog
+
+function recordError(source: string, err: unknown, info?: string) {
+  const e = err as { message?: string; stack?: string } | undefined
+  const message = (e?.message ?? String(err)) || 'unknown error'
+  const entry: ArchyErrorEntry = { when: new Date().toISOString(), source, message, info, stack: e?.stack }
+  errorLog.push(entry)
+  if (errorLog.length > 25) errorLog.shift()
+  console.error(`[${source}]`, err, info ?? '')
+  // Surface the real message (truncated) instead of a generic toast — this is a
+  // test/bug-bash build, and "Something went wrong" hides exactly what we need.
+  const short = message.length > 140 ? `${message.slice(0, 140)}…` : message
+  try {
+    useToast().error(`Something went wrong: ${short}`)
+  } catch { /* toast itself failed — the console + ring buffer still have it */ }
 }
 
+app.config.errorHandler = (err, _instance, info) => recordError('Vue Error', err, info)
+
+// Vue's errorHandler only catches errors raised synchronously inside Vue's
+// lifecycle/reactivity. Async rejections and plain runtime errors (e.g. a JS
+// API missing in an older WebView) slip past it, so catch those too.
+window.addEventListener('error', (ev) => recordError('window.error', ev.error ?? ev.message))
+window.addEventListener('unhandledrejection', (ev) => recordError('unhandledrejection', ev.reason))
+
 app.mount('#app')