feat: add Procedure Duration/Time Slot settings and custom appointment type

- Add Settings > Advanced > Procedure Duration/Time Slot page with three sections:
  1. Procedure Duration: CDT codes with durations (editable table, save per section)
  2. Doctor Time Slot: drag-to-block visual grid (A/B/C columns, 8 AM–9 PM, edit/delete slots)
  3. Hygienist Time Slot: procedure descriptions with durations
- Backend: ProcedureTimeslot Prisma model, storage, and GET/PUT /api/procedure-timeslot route
- DB migration: procedure_timeslot table
- Appointment form: when type is "Other", show a free-text input for custom description; saved as other:<description> and decoded for display on the schedule card

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/Backend/src/routes/index.ts

@@ -28,6 +28,7 @@ import twilioRoutes from "./twilio";
 import aiSettingsRoutes from "./ai-settings";
 import officeHoursRoutes from "./office-hours";
 import officeContactRoutes from "./office-contact";
+import procedureTimeslotRoutes from "./procedure-timeslot";
 
 const router = Router();
 
@@ -60,5 +61,6 @@ router.use("/twilio", twilioRoutes);
 router.use("/ai", aiSettingsRoutes);
 router.use("/office-hours", officeHoursRoutes);
 router.use("/office-contact", officeContactRoutes);
+router.use("/procedure-timeslot", procedureTimeslotRoutes);
 
 export default router;