fix(tunnel): make tailscale probes non-blocking to prevent UI freeze

Convert isTailscaleLoggedIn to cached non-blocking getter and turn
isTailscaleRunningStrict / isTailscaleLoggedInStrict into async execAsync
probes. The status poll no longer blocks the event loop, so dashboard
navigation stays responsive while tunnel/tailscale checks run.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/shared/services/initializeApp.js

@@ -173,7 +173,7 @@ async function safeRestartTailscale(reason) {
 
   // Tailscale daemon is OS-level with built-in reconnect; trust it when running (even on netchange).
   // Startup uses strict probe — cached state is cold after process/dev reload.
-  const running = reason === "startup" ? isTailscaleRunningStrict() : isTailscaleRunning();
+  const running = reason === "startup" ? await isTailscaleRunningStrict() : isTailscaleRunning();
   if (running) return;
 
   const force = FORCE_RESTART_REASONS.test(reason);