refactor(tiles): removeTile has no auto option, its refocus is always the app's

removeTile took `auto` for the neighbour it focuses, but no caller ever
passed anything but true: a tile leaving is never a human picking its
neighbour. The option is gone (the refocus passes `auto: true` itself, and
the doc comment says so), and the four call sites that spelled out the
defaults (the header's ×, remove-tile, a stopped socket, a popped-out
session) are plain removeTile(id). `refocus: false` callers are unchanged.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/web/public/app.js

@@ -1708,7 +1708,7 @@ class CodemanApp {
     if (on) this.detachedSessions.add(id); else this.detachedSessions.delete(id);
     // A popped-out session's window owns its PTY size now, so it leaves the
     // tile grid (one place per session in this browser tab).
-    if (on && this._tileGrid?.has(id)) this.removeTile(id, { refocus: true, auto: true });
+    if (on && this._tileGrid?.has(id)) this.removeTile(id);
     const container = this.$('sessionTabs');
     const tab = container && container.querySelector(`.session-tab[data-id="${id}"]`);
     if (tab) tab.classList.toggle('detached', on);