fix(app): refresh open session messages on resume/reconnect

[chphch]

Messages an agent produces while the Happy app is backgrounded don't appear when you return to the app — the open chat stays stale until you leave and re-enter the session. The cause is a misdirected refresh trigger: SessionView's effect that re-fetches an open session's messages depends on realtimeStatus, but realtimeStatus tracks the LiveKit voice session (storage.ts useRealtimeStatus, written only by RealtimeVoiceSession*/RealtimeSession) — not the data socket, whose status lives in the separate socketStatus/useSocketStatus. So on app resume (or any socket reconnect), that effect never re-runs, and sync.ts's onReconnected handler deliberately skipped refreshing the open session's messages, with a comment that relied on exactly this dead trigger (onSessionVisible "called by SessionView when realtimeStatus changes"). Re-entering the session works only because a fresh mount re-fetches. This fix refreshes the currently-viewing session's messages on both AppState → 'active' and the socket onReconnected path via onSessionVisible(currentViewingSessionId) (a bounded forward sync). It also covers a foreground network blip that reconnects with recovered=false (server connection-state recovery off), which had the same gap.

Proof

Verified end-to-end on a throwaway standalone happy-server (PGlite) + Expo web + a paired happy-cli daemon, driven with Playwright. Two browser contexts on one account: context A opens a session then goes offline (simulating the app being backgrounded); context B (online) sends a marked message to that session; context A comes back online. The missed message now renders on A on reconnect without a remount (onSessionVisible → fetchForwardSince). Screenshots/GIF in the PR comment below — A shows "No messages yet" while offline, then the full conversation (including the message it missed) after reconnect. pnpm typecheck clean.

[chphch]

Proof — before / after

Captured on a standalone happy-server (PGlite) + Expo web + a paired happy-cli daemon, driven with Playwright. Methodology that isolates this fix specifically:

1. Context A opens a session and primes it with a message so it is already-loaded (sessionLastSeq set) — the user's real condition. (The custom session-prefetch only fetches never-loaded sessions, so an empty session would be refreshed by prefetch and mask the fix.)
2. The agent is then stopped, so nothing answers later messages (no post-reconnect update to trigger handleUpdate's gap-refresh).
3. A goes offline for >45s (past the server pingTimeout) so the socket is genuinely disconnected — a shorter pause keeps the socket alive and the broadcast is merely buffered, which masks the bug.
4. Context B sends a marked message to the same session while A is disconnected, so A truly misses it.
5. A comes back online (resume).

Without the fix (top): after reconnect A is stale — the message that arrived while A was away is missing; it only appears after leaving and re-entering the session. With the fix (bottom): the missed message renders automatically on reconnect, no remount. The only change between the two runs is sync.ts (verified: the served bundle contained the fix in the "after" run and not in the "before" run). pnpm typecheck clean.