feat(calendar): expose an accessible calendar picker

webui/tests/calendar-picker-structure.test.mjs

@@ -0,0 +1,20 @@
+import fs from "node:fs";
+
+function assert(condition, message) {
+  if (!condition) throw new Error(message);
+}
+
+const picker = fs.readFileSync(new URL("../src/features/calendar/CalendarPicker.tsx", import.meta.url), "utf8");
+const moduleSource = fs.readFileSync(new URL("../src/module.ts", import.meta.url), "utf8");
+const coreTypes = fs.readFileSync(new URL("../../../govoplan-core/webui/src/types.ts", import.meta.url), "utf8");
+
+assert(moduleSource.includes('"calendar.picker": calendarPicker'), "Calendar must register the named picker capability");
+assert(coreTypes.includes("export type CalendarPickerUiCapability"), "Core must expose the narrow cross-module contract");
+assert(picker.includes("listCalendars(settings)"), "Picker must use Calendar's authenticated list API");
+assert(picker.includes("hasScope(auth, CALENDAR_PICKER_READ_SCOPE)"), "Picker must avoid loading without read permission");
+assert(picker.includes("value={value}"), "Picker must remain controlled by its consumer");
+assert(picker.includes("onChange={(event) => onChange(event.target.value)}"), "Picker must return the chosen calendar id");
+assert(picker.includes("aria-busy={loading || undefined}"), "Picker must expose loading state accessibly");
+assert(picker.includes("aria-describedby={status ? statusId : undefined}"), "Picker must associate availability feedback");
+
+console.log("Calendar picker capability structure checks passed.");