COD-47 replay full tmux scrollback on terminal reload

A full page reload (GET /api/sessions/:id/terminal with no ?tail=) now captures
the ENTIRE tmux scrollback via capture-pane -p -e -S -, so users get back history
that scrolled off Codeman's byte buffer. Tab switches (?tail=N) keep the fast
visible-frame capture.

- tmux-manager capturePaneBuffer/captureActivePaneBuffer take { fullHistory }:
  full-history returns raw linear scrollback (skips the single-screen
  formatPaneSnapshot repaint, which would clip multi-screen history).
- /terminal selects full-history on full reload, visible on tail; caps the
  payload at the configured terminalBufferMaxBytes (keeps most-recent bytes,
  line-aligned) and returns source/fullSize/truncated metadata.

Verified: tsc 0, tmux-capture-full-history 5/5, session-routes 68/68.
Caveat: lines tmux already evicted past its history-limit can't be recovered.

src/mux-interface.ts

@@ -225,9 +225,16 @@ 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 a pane's current tmux buffer with ANSI escape codes preserved.
+   * Pass `{ fullHistory: true }` to capture the entire scrollback (`-S -`)
+   * as linear text instead of just the visible single-screen frame (COD-47).
+   */
+  capturePaneBuffer?(muxName: string, paneTarget?: string, opts?: { fullHistory?: boolean }): string | null;
 
-  /** Capture the active pane's current tmux buffer with ANSI escape codes preserved. */
-  captureActivePaneBuffer?(muxName: string): string | null;
+  /**
+   * Capture the active pane's current tmux buffer with ANSI escape codes preserved.
+   * Pass `{ fullHistory: true }` to capture the entire scrollback (COD-47).
+   */
+  captureActivePaneBuffer?(muxName: string, opts?: { fullHistory?: boolean }): string | null;
 }