fix(boot): native offline-first launch is silent and fast (Android 10)

Two native offline-first boot glitches (seen on Android 10):
- bootOffline forced offlineNoNetwork, so its first successful reconcile healed to online with a
  spurious "back online" toast on a first launch that actually had connectivity. The boot-assumed
  offline is now PROVISIONAL: the first probe confirms it — a success heals silently (nothing to
  come back from), a failure turns it into a real offline whose later recovery does toast.
- A native launch with a cached guest session (no email) skipped the offline short-circuit and hung
  ~25 s on adoptSession's retrying profile fetch in airplane mode. The native channel is offline-first,
  so it now takes the same reachability-gated fallback (~3 s bound) as an installed email PWA.

ui/src/lib/app.svelte.ts

@@ -982,7 +982,11 @@ export async function bootstrap(): Promise<void> {
     // to online when the network returns. Web-only reaches here (the Mini-App branches returned above),
     // so isStandalone gates it.
     const cachedProfile = await loadProfile();
-    const canOffline = !!cachedProfile && !vkcb && isStandalone() && !!cachedProfile.email;
+    // A native app is offline-first, so a native launch — even a guest with no email — must fall back
+    // to the cached session's offline lobby rather than hang ~25 s on adoptSession's retrying profile
+    // fetch when the device is offline (e.g. airplane mode). Web keeps the installed-PWA + email gate.
+    const nativeChannel = clientChannel() === 'android' || clientChannel() === 'ios';
+    const canOffline = !vkcb && (nativeChannel || (!!cachedProfile && isStandalone() && !!cachedProfile.email));
     if (canOffline) {
       const interfaceOffline = typeof navigator !== 'undefined' && navigator.onLine === false;
       gateway.setToken(saved.token);