fix(terminal): reattach recovered daemon sessions on relaunch + tmux persistence/stability batch

[openwong2kim]

Summary

Fixes the blank-terminal-on-relaunch bug the user hit in dogfood: after the
daemon restarts (reboot / crash / old-app shutdown) and recovers its sessions,
npm start showed blank terminals with no scrollback. Persistence, daemon
reconnect, and session recovery were all working — the renderer just never
re-attached to the recovered sessions, so it looked broken.

This PR lands that fix plus the tmux-style persistence work and the dogfood
stability batch that were verified alongside it in the same running app.

Root cause (the blank terminal)

The mount-time daemon reattach lived inside the terminal-creation effect:

if (daemonModeAtMount) {
  reconnectPtyWithRetry(ptyId, () => terminalRef.current === terminal);
}

reconnectPtyWithRetry checks its isCurrent guard synchronously on the
first line (if (!isCurrent()) return). But that call ran before the same
effect's later terminalRef.current = terminal assignment, so on every fresh
mount the guard was false, the retry bailed immediately, and pty.reconnect
was never called. The daemon never attached a SessionPipe to the recovered
session → no RingBuffer replay → blank pane. pty.create still worked, which
is why only restored sessions went blank.

Fix: move the reattach into a dedicated effect that runs after the mount
effect (so terminalRef is set), fire it when daemon mode is active at mount
or on a later daemon:connected (fresh-daemon-spawn startup race /
mid-session respawn), and guard with terminalRef.current !== null.

What's in here

fix(terminal) — blank-terminal fix (commit 2)

• Dedicated daemon-reattach effect in useTerminal (the real fix).
• Process-wide WebGL context LRU pool (cap 12) so restoring many sessions can't
  blow Chromium's ~16-context limit and blank panes via forced eviction;
  over-budget terminals fall back to xterm's DOM renderer.
• plans/persistence-beyond-tmux.md — persistence roadmap (R1 never-self-kill
  daemon, R2 session-host process for live-process survival across daemon death).

feat(persistence) — tmux-style detach + dogfood batch (commit 1)

• Quit now detaches (daemon + live sessions survive, next launch reattaches);
  only the tray "Shut down wmux" tears the daemon down, with a pid-kill backstop.
• Drop the per-pane token chip (TokenTracker/tokenSlice), Ctrl+arrow pane
  navigation + cheat-sheet entries, right-click copy that keeps the selection,
  RSS memory reporting, completed-agent border blink.

Verification

• GUI dogfood: terminals now show their restored scrollback after a daemon
  restart (user-confirmed). Daemon log shows attachSession + a 104 KB
  SessionPipe.flush per recovered session.
• Tests: 2047 passing (164 files) + tsc clean. New source-level regression
  lock useTerminal.daemonReattach.test.ts (reattach must run after terminalRef
  is set, never with the assigned-later === terminal guard) + 8-test WebGL pool
  unit suite + the detach invariants in beforeQuitDisconnectRace / shutdownRpc.

Notes / follow-ups (not in this PR)

• A handful of WebGL "too many active contexts" warnings still appear during the
  startup burst (GPU context disposal lags JS disposal). Cosmetic — terminals are
  not blank (DOM-renderer fallback). Tunable later.
• R1 (daemon must not self-kill a wedged-but-live daemon) and R2 (session-host
  process) are scoped in the design doc, not implemented here.

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