fix(05-review): NEW-WR-01 emit delete changes when server returns zero events (whole-cache clear)

Pre-capture all currently-cached rows into pendingDeleteRows before the whole-cache
db.delete() when seenUids.length === 0. The existing >0 branch behavior is unchanged.
Adds a regression test verifying onChanges receives one delete change per cached row
on a full-calendar clear.

apps/api/src/broker/sync.ts

@@ -256,6 +256,14 @@ export async function syncCalendar(
           notInArray(calendarEvents.uid, seenUids),
         ),
       )
+  } else if (onChanges) {
+    // NEW-WR-01: server returned zero events → entire calendar cache will be cleared.
+    // Capture ALL currently-cached rows before the delete so delete-change events
+    // are emitted for each one. Without this, bulk/clear deletions were silently dropped.
+    pendingDeleteRows = await db
+      .select({ uid: calendarEvents.uid, title: calendarEvents.title })
+      .from(calendarEvents)
+      .where(eq(calendarEvents.calendarId, cal.id))
   }
 
   if (seenUids.length > 0) {