feat(appointments): add FBA creation and destination filtering

src/modules/appointment-calendar/calendar.test.ts

@@ -2,12 +2,17 @@ import { describe, expect, it } from 'vitest'
 import { addDays, calendarDates, calendarRange, moveCalendar } from './calendar'
 
 describe('appointment calendar', () => {
-  it('shows six complete Monday-first weeks across year boundaries', () => {
-    const dates = calendarDates('2027-01-15', 'month')
-    expect(dates).toHaveLength(42)
-    expect(dates[0]).toBe('2026-12-28')
-    expect(dates.at(-1)).toBe('2027-02-07')
-    expect(calendarRange('2027-01-15', 'month').to).toBe('2027-02-08')
+  it.each([
+    ['2026-10-19', '2026-09-28', '2026-11-02', 35],
+    ['2027-01-15', '2026-12-28', '2027-02-01', 35],
+    ['2027-02-15', '2027-02-01', '2027-03-01', 28],
+    ['2026-08-15', '2026-07-27', '2026-09-07', 42],
+  ] as const)('shows only the complete weeks needed for %s', (anchor, from, to, count) => {
+    const dates = calendarDates(anchor, 'month')
+    expect(dates).toHaveLength(count)
+    expect(dates[0]).toBe(from)
+    expect(dates.at(-1)).toBe(addDays(to, -1))
+    expect(calendarRange(anchor, 'month')).toEqual({ from, to })
   })
 
   it('moves by a week in week mode instead of following the prototype month-navigation bug', () => {