feat(photos): modern confirm dialog + correct lightbox favorite state

- Add Modal.confirmDialog() (Promise<boolean>, built on openPanel so it
  inherits the overlay, animation, focus-trap and Escape handling) and use
  it to replace native confirm() in the photos batch-delete and lightbox
  single-delete flows.
- The lightbox now reflects the real favorite state when an item opens
  (previously the star always started empty) and toggles favorites through
  the favorites module so its cache stays in sync.
- Add photos.delete_* i18n keys (English; other locales fall back to en).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JW6ghFMDtnRYuYNzZhb47M

static/locales/en.json

@@ -68,7 +68,10 @@
         "items_selected": "selected",
         "view_daily": "Day",
         "view_monthly": "Month",
-        "view_yearly": "Year"
+        "view_yearly": "Year",
+        "delete_title": "Move to Trash",
+        "delete_selected_confirm": "Move the selected items to Trash?",
+        "delete_one_confirm": "Move \"{{name}}\" to Trash?"
     },
     "music": {
         "create_playlist": "Create Playlist",