fix(11): make CI green — pin TZ in all-day scheduler tests, drop redundant casts

fast-checks failed on 3 no-unnecessary-type-assertion ESLint errors (reminderIsCustom is now a real CalendarOccurrence field). api failed on 4 all-day 9 AM-local tests that assumed a UTC-4 host; CI runs UTC. Pin process.env.TZ=America/New_York in the all-day describe (production code reads TZ at call time, D-04).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/api/tests/broker/reminderScheduler.test.ts

@@ -659,8 +659,13 @@ describe('reminderScheduler — NOTIF-06: all-day 9 AM-local fire branch', () =>
   // All-day tests use the server timezone (America/New_York = UTC-4 in summer).
   // computeAlertInstantUtc('2026-06-15', 0, 'America/New_York') = 2026-06-15T13:00:00Z.
   // Tests set `now` to the expected alert UTC to trigger the fire window.
+  // Pin TZ explicitly so these assertions are deterministic regardless of the host/CI
+  // timezone (CI runs UTC; the scheduler reads process.env.TZ at call time, D-04).
+  let prevTz: string | undefined;
 
   beforeEach(() => {
+    prevTz = process.env.TZ;
+    process.env.TZ = 'America/New_York';
     vi.useFakeTimers();
     vi.resetModules();
   });
@@ -668,6 +673,8 @@ describe('reminderScheduler — NOTIF-06: all-day 9 AM-local fire branch', () =>
   afterEach(() => {
     vi.useRealTimers();
     vi.clearAllMocks();
+    if (prevTz === undefined) delete process.env.TZ;
+    else process.env.TZ = prevTz;
   });
 
   it('all-day 0-lead fires at 9 AM local (not midnight) on event date', async () => {