feat(05-01): add push_subscriptions table + calendar_events.title column; VAPID env wiring

- schema.ts: new pushSubscriptions mysqlTable (user_id FK cascade, endpoint unique, p256dh, auth)
- schema.ts: add nullable title varchar(500) to calendarEvents after rawVevent (D-02/NOTIF-01)
- 0003_same_xavin.sql: CREATE TABLE push_subscriptions + ALTER calendar_events ADD title
- migration applied to dev DB via db:generate + db:migrate (NOT db:push per anti-pattern)
- docker-compose.yml: inject VAPID_PUBLIC_KEY/PRIVATE_KEY/SUBJECT into api environment block
- .env.example: document all three VAPID vars with placeholders + generation instructions

apps/api/src/db/schema.ts

@@ -119,6 +119,9 @@ export const calendarEvents = mysqlTable(
     etag: varchar('etag', { length: 256 }),
     objectUrl: varchar('object_url', { length: 1024 }), // CalDAV object URL; populated from obj.url by sync.ts (D-08)
     rawVevent: text('raw_vevent').notNull(), // full VCALENDAR/VEVENT string for ical.js
+    // Readable event title extracted from VEVENT SUMMARY by sync.ts (D-02/NOTIF-01).
+    // Nullable: populated by Phase 5 sync update; pre-existing rows remain NULL until resynced.
+    title: varchar('title', { length: 500 }),
     dtstartUtc: timestamp('dtstart_utc'), // NULL for all-day events
     dtstartDate: date('dtstart_date'), // set for all-day events; NULL for timed
     allDay: boolean('all_day').default(false).notNull(),
@@ -223,6 +226,33 @@ export const listShares = mysqlTable(
   ],
 )
 
+/**
+ * Push notification subscriptions (Phase 5 — Web Push).
+ *
+ * Member-count-agnostic (D-18): one row per browser push subscription endpoint.
+ * endpoint is globally unique — a single device endpoint belongs to exactly one user.
+ * Cascade delete on user removal keeps subscriptions clean without orphan cleanup jobs.
+ */
+export const pushSubscriptions = mysqlTable(
+  'push_subscriptions',
+  {
+    id: int().primaryKey().autoincrement(),
+    userId: int('user_id')
+      .notNull()
+      .references(() => users.id, { onDelete: 'cascade' }),
+    endpoint: text('endpoint').notNull(),
+    p256dh: text('p256dh').notNull(),
+    auth: varchar('auth', { length: 256 }).notNull(),
+    createdAt: timestamp('created_at').defaultNow().notNull(),
+    updatedAt: timestamp('updated_at').defaultNow().onUpdateNow(),
+  },
+  (t) => [
+    // One endpoint is globally unique — a single device maps to exactly one subscription row
+    unique('uniq_push_endpoint').on(t.endpoint),
+    index('idx_push_subscriptions_user_id').on(t.userId),
+  ],
+)
+
 /**
  * Items within a list.
  *