feat: appointment confirmation and cancellation (GH #98, GRO-153)

Add customer confirmation/cancellation flow for appointments:

- DB migration (0013): add confirmation_status, confirmed_at, cancelled_at,
  confirmation_token to appointments table with index on token column
- schema.ts + factories.ts + types: expose new columns and ConfirmationStatus type
- GET /api/book/confirm/:token — tokenized confirm via email link (redirects)
- GET /api/book/cancel/:token — tokenized cancel via email link, single-use token
- POST /api/appointments/:id/confirm — portal/staff confirm endpoint
- POST /api/appointments/:id/cancel — portal/staff cancel endpoint
- Reminder emails now include Confirm/Cancel CTA buttons with tokenized links
- Reminder service generates confirmation token if missing before sending
- Staff calendar shows confirmation status indicator on appointment cards
  and in the detail modal (confirmed ✓ / customer cancelled ✗)
- /booking/confirmed, /booking/cancelled, /booking/error redirect pages
- 23 new unit tests covering all new endpoints and edge cases

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/db/src/factories.ts

@@ -136,6 +136,10 @@ export function buildAppointment(
     endTime,
     notes: null,
     priceCents: null,
+    confirmationStatus: "pending",
+    confirmedAt: null,
+    cancelledAt: null,
+    confirmationToken: null,
     createdAt: new Date("2025-01-01T00:00:00Z"),
     updatedAt: new Date("2025-01-01T00:00:00Z"),
   };

packages/db/src/schema.ts

@@ -162,6 +162,13 @@ export const appointments = pgTable("appointments", {
   groupId: uuid("group_id").references(() => appointmentGroups.id, {
     onDelete: "set null",
   }),
+  // Customer confirmation/cancellation tracking
+  // Values: "pending" | "confirmed" | "cancelled"
+  confirmationStatus: text("confirmation_status").notNull().default("pending"),
+  confirmedAt: timestamp("confirmed_at"),
+  cancelledAt: timestamp("cancelled_at"),
+  // Token for tokenized email confirm/cancel links (no auth required)
+  confirmationToken: text("confirmation_token").unique(),
   createdAt: timestamp("created_at").notNull().defaultNow(),
   updatedAt: timestamp("updated_at").notNull().defaultNow(),
 });