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/mux-interface.ts

@@ -192,6 +192,12 @@ export interface TerminalMultiplexer extends EventEmitter {
    */
   getAttachArgs(muxName: string): string[];
 
+  /** Pin a mux window so client attaches do not automatically dictate its size. */
+  setManualWindowSize?(muxName: string): boolean;
+
+  /** Explicitly resize a mux window after Codeman accepts a terminal resize. */
+  resizeWindow?(muxName: string, cols: number, rows: number): boolean;
+
   // ========== Availability ==========
 
   /** Check if the multiplexer binary is available on the system */
@@ -205,4 +211,10 @@ export interface TerminalMultiplexer extends EventEmitter {
 
   /** Respawn a dead pane with a fresh command. Returns the new PID or null on failure. */
   respawnPane(options: RespawnPaneOptions): Promise<number | null>;
+
+  /** Capture a pane's current tmux buffer with ANSI escape codes preserved. */
+  capturePaneBuffer?(muxName: string, paneTarget: string): string | null;
+
+  /** Capture the active pane's current tmux buffer with ANSI escape codes preserved. */
+  captureActivePaneBuffer?(muxName: string): string | null;
 }