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>

ts/globals.d.ts

@@ -4,5 +4,10 @@ declare global {
   interface Window {
     fetchWithHtmxTriggers(input: RequestInfo | URL, init?: RequestInit): Promise<Response>;
     readSearchSelect(form: HTMLElement): void;
+    applyFilterBar(event: Event): boolean;
+    clearFilterBar(formId: string, filterInputId: string): void;
+    toggleStringFilterInput(radio: HTMLInputElement): void;
+    showPresetNameInput(): void;
+    savePreset(formId: string, filterInputId: string, saveUrl: string): void;
   }
 }