Convert year_picker to TypeScript; drop inline f-string script (issue #17)

- Add ts/year_picker.ts: typed onSwap port of the year-picker glue. Datepicker
  declared as an ambient global (vendored UMD); PickerElement types the
  _pickerInstance prop the Alpine toggle button reaches
- Remove the duplicate inline <script> from the YearPicker component (was a JS
  blob in a Python f-string — the CLAUDE.md anti-pattern) and the orphaned
  games/static/js/year_picker.js that nothing loaded; the component now declares
  dist/year_picker.js as media alongside the datepicker UMD bundle
- Module defer semantics keep the classic UMD bundle running before the
  deferred year_picker module, so Datepicker is defined in time

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

games/static/js/year_picker.js

@@ -1,38 +0,0 @@
-import { onSwap } from "./utils.js";
-
-onSwap("#year-picker-input", function(pickerEl) {
-    const selectedYear = pickerEl.dataset.selectedYear;
-    const urlTemplate = pickerEl.dataset.urlTemplate;
-    const currentYear = new Date().getFullYear();
-    const availableYears = new Set(
-        pickerEl.dataset.availableYears
-            .split(",")
-            .map(s => parseInt(s.trim()))
-            .filter(n => !isNaN(n))
-    );
-
-    const picker = new Datepicker(pickerEl, {
-        pickLevel: 2,
-        format: "yyyy",
-        minDate: new Date(1999, 0, 1),
-        maxDate: new Date(currentYear, 11, 31),
-        autohide: false,
-        orientation: "bottom end",
-        showOnClick: false,
-        showOnFocus: false,
-        beforeShowYear: (date) => ({ enabled: availableYears.has(date.getFullYear()) }),
-    });
-    pickerEl._pickerInstance = picker;
-
-    picker.element.addEventListener("changeDate", (event) => {
-        const year = event.detail.date?.getFullYear();
-        if (year && urlTemplate) {
-            window.location.href = urlTemplate.replace("__year__", year);
-        }
-    });
-
-    if (selectedYear) {
-        picker.dates = [new Date(parseInt(selectedYear), 0, 1)];
-        picker.update();
-    }
-});