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>

ts/year_picker.ts

@@ -0,0 +1,54 @@
+/**
+ * YearPicker — wires the Flowbite-datepicker year grid behind the YearPicker
+ * component (common/components/primitives.py). The component renders a hidden
+ * #year-picker-input carrying data-available-years / data-selected-year /
+ * data-url-template; this turns it into a year-level Datepicker and navigates
+ * to the chosen year's URL. Datepicker comes from the vendored UMD bundle
+ * (datepicker.umd.js), loaded as a classic script before this module runs.
+ */
+import { onSwap } from "./utils.js";
+
+declare const Datepicker: any;
+
+// The Alpine toggle button reaches the Datepicker instance through this prop.
+interface PickerElement extends HTMLInputElement {
+  _pickerInstance?: any;
+}
+
+onSwap("#year-picker-input", (element) => {
+  const pickerElement = element as PickerElement;
+  const selectedYear = pickerElement.dataset.selectedYear;
+  const urlTemplate = pickerElement.dataset.urlTemplate;
+  const currentYear = new Date().getFullYear();
+  const availableYears = new Set(
+    (pickerElement.dataset.availableYears ?? "")
+      .split(",")
+      .map((part) => parseInt(part.trim(), 10))
+      .filter((year) => !isNaN(year))
+  );
+
+  const picker = new Datepicker(pickerElement, {
+    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: Date) => ({ enabled: availableYears.has(date.getFullYear()) }),
+  });
+  pickerElement._pickerInstance = picker;
+
+  picker.element.addEventListener("changeDate", (event: Event) => {
+    const year = (event as CustomEvent).detail.date?.getFullYear();
+    if (year && urlTemplate) {
+      window.location.href = urlTemplate.replace("__year__", String(year));
+    }
+  });
+
+  if (selectedYear) {
+    picker.dates = [new Date(parseInt(selectedYear, 10), 0, 1)];
+    picker.update();
+  }
+});