Quest dialogs: stay centred, clickable, closable with Esc

- Quest dialogs are tooltips. A tooltip now keeps the offset it gets when it
  becomes visible (the hovered window's, or centred for dialogs) and records
  it for hit tests; its own event handler is shifted too. Hidden windows no
  longer count as hovered.
- Esc closes a visible dialog the way its answer buttons do: hide, then
  cDialogManager::Answer with no answer (ends the input lock, nothing chosen).
- Autotest can select a save game row (-Save).
- Names for the UI manager, tooltip and dialog functions.

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

src/mods/hud.h

@@ -13,4 +13,8 @@ int CursorOffsetX();
 // window, a private copy with x shifted by CursorOffsetX().
 void* CursorFor(void* cursor);
 
+// Tooltips that are dialogs of their own (e.g. quest dialogs: they became
+// visible while no moved window was under the cursor) and are visible now.
+int VisibleDialogTooltips(void** out, int max);
+
 } // namespace mods::hud