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>

common/components/custom_elements.py

@@ -189,6 +189,18 @@ register_element("filter-bar", "FilterBar", FilterBarProps)
 _FilterBarElement = custom_element_builder("filter-bar")
 
 
+class YearPickerProps(TypedDict):
+    selected_year: str  # "" for the all-time/empty state
+    available_years: str  # csv, e.g. "2019,2020"
+    url_template: str  # contains the literal __year__ placeholder
+
+
+# The <year-picker> builder lives in primitives.py (next to YearPicker, which
+# uses it) because custom_elements imports from primitives — registering here
+# would be a circular import. Registration is codegen-only, so it belongs here.
+register_element("year-picker", "YearPicker", YearPickerProps)
+
+
 def SelectionFields(
     *,
     source: str,