Convert filter_bar.js to TypeScript (issue #17)

- Add ts/filter_bar.ts: typed port of the filter bar. Criterion / PillEntry /
  RangeField / DeselectableRadio interfaces replace the loose objects and the
  radio.wasChecked custom property; var → const/let throughout
- Window entry points (applyFilterBar/clearFilterBar/toggleStringFilterInput/
  showPresetNameInput/savePreset) declared in ts/globals.d.ts; readSearchSelect
  now called as window.readSearchSelect
- Drop the dead selectValue helper; factor the repeated path→mode mapping into
  presetMode()
- Point the FilterBar component Media and every e2e/test reference at the
  compiled dist/filter_bar.js

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_rendered_pages.py

@@ -63,7 +63,7 @@ class RenderedPagesTest(TestCase):
         """The games list view passes no scripts= argument; the filter bar's
         components declare their JS and Page() collects it."""
         html = self.get("games:list_games").content.decode()
-        self.assertIn("js/filter_bar.js", html)
+        self.assertIn("js/dist/filter_bar.js", html)
         self.assertIn("js/dist/search_select.js", html)
         self.assertIn("js/range_slider.js", html)