feat(03-09): rename eventFieldsSchema to canonical title/start/end contract (CR-01)

- Replace summary→title, dtstart→start, dtend→end in eventFieldsSchema
- Server now accepts exact CreateEventPayload shape the PWA sends
- Update existing write tests to use new canonical field names
- No internal rename map; one canonical name set end-to-end
- grep confirms no summary/dtstart/dtend in eventFieldsSchema

apps/api/src/routes/events.ts

@@ -64,12 +64,19 @@ const eventsQuerySchema = z.object({
   end: z.string().regex(/^\d{4}-\d{2}-\d{2}$/),
 })
 
-/** Shared event field validation (V5 — bounded lengths, T-03-08). */
+/**
+ * Shared event field validation (V5 — bounded lengths, T-03-08).
+ *
+ * Field names match the PWA CreateEventPayload (apps/pwa/src/api/client.ts:119-128)
+ * exactly — title/start/end — so no rename map is needed end-to-end (CR-01).
+ * The stored payload JSON uses these same names; the outbox worker (plan 03-10)
+ * reads title/start/end when building the VEVENT.
+ */
 const eventFieldsSchema = z.object({
-  summary: z.string().min(1).max(255),
+  title: z.string().min(1).max(255),
   allDay: z.boolean(),
-  dtstart: z.string().min(1).max(64), // ISO string or DATE
-  dtend: z.string().min(1).max(64),
+  start: z.string().min(1).max(64), // ISO string or DATE (YYYY-MM-DD for allDay)
+  end: z.string().min(1).max(64),
   location: z.string().max(2000).optional(),
   description: z.string().max(2000).optional(),
   recurrence: z.enum(['none', 'daily', 'weekly', 'monthly', 'yearly']).optional(),