feat(terminal): tmux pane-buffer primitives and session/render reliability

Mode-agnostic terminal foundation extracted from the downstream branch:
- formatPaneSnapshot: SGR/grapheme-aware tmux pane capture + active-pane
  resolution, with OSC/CSI redraw suppression and the buffer-load owner-token
  race fix on the terminal fetch path
- socket-correct tmux lifecycle: dedicated -L socket and /tmp launch cwd in
  createSession (restores the FUSE/getcwd hardening from #110), and a
  socket-aware re-attach window-size query (avoids the 120x40 flicker)
- inline-rename: commit/cancel state handling clears _activeRename and skips
  the API call on cancel
- selectSession: restored detached-window raise short-circuit

The codex-specific xterm snapshot/replay, the vendored serialize addon, and
the synchronous live pane-capture on the request path are intentionally
excluded: they depend on a 'codex' SessionMode that doesn't exist on master
and are deferred to COD-34 (which introduces that mode). The capture
primitives remain exported for COD-34 to build on.

Co-Authored-By: Saqeb Akhter <saqeb.akhter@gmail.com>

src/session.ts

@@ -1004,7 +1004,12 @@ export class Session extends EventEmitter {
     }
 
     // Attach to the mux session via PTY
-    // Query existing tmux window size so re-attach matches (avoids flicker from 120x40 default)
+    // Prevent tmux from letting the newest browser attach dictate global window
+    // size; accepted Codeman resize events update it explicitly below.
+    mux.setManualWindowSize?.(this._muxSession!.muxName);
+    // Query existing tmux window size so re-attach matches (avoids flicker from 120x40 default).
+    // MUST go through the dedicated socket (mux.muxSocket); a bare `tmux display` hits the
+    // default server, always fails for our socketed sessions, and silently falls back to 120x40.
     const { cols: ptyCols, rows: ptyRows } = queryTmuxWindowSize(this._muxSession!.muxName, mux.muxSocket);
     try {
       this.ptyProcess = pty.spawn(mux.getAttachCommand(), mux.getAttachArgs(this._muxSession!.muxName), {
@@ -2057,6 +2062,9 @@ export class Session extends EventEmitter {
     if (this.ptyProcess && (cols !== this._ptyCols || rows !== this._ptyRows)) {
       this._ptyCols = cols;
       this._ptyRows = rows;
+      if (this._mux && this._muxSession) {
+        this._mux.resizeWindow?.(this._muxSession.muxName, cols, rows);
+      }
       this.ptyProcess.resize(cols, rows);
     }
   }