Remove inline-handler → window.* contract (issue #28)

Finish the behavioural refactor from #28: no first-party JS lives on the
global object solely to be reachable from a server-rendered inline on*
attribute, and no inline Alpine blobs remain in the filter bar / year picker.

- Filter-bar collapse: drop the inline onclick for a delegated click listener
  on the persistent <filter-bar> custom element (data-filter-bar-toggle). The
  inner #filter-bar body is htmx-swapped while connectedCallback does not re-run,
  so delegation on the host preserves the swap-survival the inline handler had.
- YearPicker: convert the Alpine x-data/x-on/x-ref/_pickerInstance f-string into
  a <year-picker> custom element with typed props (YearPickerProps). Behavior
  moves to ts/elements/year-picker.ts; ts/year_picker.ts and _YEAR_PICKER_MEDIA
  are removed. The builder lives in primitives.py (next to YearPicker) to avoid a
  circular import; registration stays in custom_elements.py for codegen.
- Add bindPopupDismiss (ts/utils.ts): shared Escape + outside-click dismiss with
  a cleanup return and an extraInside hook for popups mounted on document.body.
  Adopted by date-range-picker.ts (1:1) and year-picker.ts (Datepicker popup is
  body-mounted, passed as an extra inside root).

Follow-up #49 tracks unifying popup/dismiss/positioning across the remaining
dropdown/search-select/Flowbite cases.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ts/elements/filter-bar.ts

@@ -403,6 +403,16 @@ class FilterBarElement extends HTMLElement {
     const form = this.querySelector<HTMLFormElement>("form");
     if (!form) return;
 
+    // Delegated on the persistent custom element so the toggle keeps working
+    // after the inner #filter-bar body is htmx-swapped — connectedCallback does
+    // not re-run for inner swaps, so a direct listener on the button would be
+    // lost (this is why the toggle was previously an inline onclick).
+    this.addEventListener("click", (event) => {
+      if ((event.target as Element).closest("[data-filter-bar-toggle]")) {
+        this.querySelector("#filter-bar-body")?.classList.toggle("hidden");
+      }
+    });
+
     form.addEventListener("submit", (event) => {
       event.preventDefault();
       const filter = buildFilterJSON(form);