maven: fix test mocks for CalendarEvents interface (verification)

- Add CalendarEvents method to recordingAPI in auth_test.go
- Add CalendarEvents method to fakeCore in handlers_test.go

Co-Authored-By: opencode <opencode@anthropic.com>

internal/auth/auth_test.go

@@ -354,6 +354,9 @@ func (r *recordingAPI) RecentOutcomes(_ context.Context, _ string, _ int) ([]str
 func (r *recordingAPI) RecentFacts(_ context.Context, _ int) ([]ipc.Fact, error) {
 	return nil, nil
 }
+func (r *recordingAPI) CalendarEvents(_ context.Context, _, _ time.Time) ([]ipc.Fact, error) {
+	return nil, nil
+}
 func (r *recordingAPI) RecentNudges(_ context.Context, _ int) ([]ipc.Nudge, error) {
 	return nil, nil
 }