feat: master data endpoint — cached departments, doctors, clinics

Redis-cached (5min TTL) lookups via /api/masterdata/departments,
/api/masterdata/doctors, /api/masterdata/clinics. Warms cache on
startup. Frontend dropdowns use these instead of hardcoded lists.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/masterdata/masterdata.controller.ts

@@ -0,0 +1,45 @@
+import { Controller, Get, Query, Logger } from '@nestjs/common';
+import { MasterdataService } from './masterdata.service';
+
+@Controller('api/masterdata')
+export class MasterdataController {
+    private readonly logger = new Logger(MasterdataController.name);
+
+    constructor(private masterdata: MasterdataService) {}
+
+    @Get('departments')
+    async departments() {
+        return this.masterdata.getDepartments();
+    }
+
+    @Get('doctors')
+    async doctors() {
+        return this.masterdata.getDoctors();
+    }
+
+    @Get('clinics')
+    async clinics() {
+        return this.masterdata.getClinics();
+    }
+
+    // Available time slots for a doctor on a given date.
+    // Computed from DoctorVisitSlot entities (doctor × clinic × dayOfWeek).
+    // Returns 30-min slots within the doctor's visiting window for that day.
+    //
+    // GET /api/masterdata/slots?doctorId=xxx&date=2026-04-15
+    @Get('slots')
+    async slots(
+        @Query('doctorId') doctorId: string,
+        @Query('date') date: string,
+    ) {
+        if (!doctorId || !date) return [];
+        return this.masterdata.getAvailableSlots(doctorId, date);
+    }
+
+    // Force cache refresh (admin use)
+    @Get('refresh')
+    async refresh() {
+        await this.masterdata.invalidateAll();
+        return { refreshed: true };
+    }
+}