feat(maestro): drop retained worktrees and header debug toggle

Removes the retained-worktree store end to end: the daemon's state-dir
store, GET/DELETE /api/worktrees, `maestro worktrees list|reclaim`, the
TUI overlay behind `w`, and the web `#/worktrees` view and header link.

The kill guard stays. A forced kill and a dirty natural exit now leave
the worktree on disk untouched instead of parking it in a store, so
removing one is an ordinary `git worktree remove`. A pristine tree is
still removed on exit. DELETE /api/sessions/:id always answers 204.

The header's debug button also goes; Ctrl+Shift+D and `?hud` still
toggle the HUD.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/src/api.ts

@@ -9,7 +9,6 @@ import type {
   NameBatch,
   Projects,
   RecentDirs,
-  RetainedWorktree,
   Session,
   Uuid,
 } from "./types.js";
@@ -112,22 +111,4 @@ export async function fetchBranches(path: string): Promise<Branches> {
   return jsonOrError(await fetch(url, { credentials: "same-origin" }));
 }
 
-/** The daemon's retained worktrees (#80): trees kept after a session ended
- * with unsaved work, with what is currently in the way. Drives the
- * retained-worktrees view (#84). */
-export async function listWorktrees(): Promise<RetainedWorktree[]> {
-  return jsonOrError(await fetch(routes.WORKTREES, { credentials: "same-origin" }));
-}
-
-/** Reclaim a retained worktree: removes its directory and drops the store
- * entry. Never deletes the branch (docs/WORKTREES.md). */
-export async function reclaimWorktree(id: Uuid): Promise<void> {
-  await jsonOrError(
-    await fetch(routes.worktree(id), {
-      method: "DELETE",
-      credentials: "same-origin",
-    }),
-  );
-}
-
 export { eventsWsUrl } from "./routes.js";