feat: platform backbone and field capture, first part (checkpoint)

Platform backbone (plan 2026-10-13-plattform-rueckgrat), reviewed tasks:
- run roles api/worker/job/all with shared startup checks (Task 1)
- schema and migration for DomainEvent, deliveries, JobRun, ThrottlerHit (Task 2)
- audit, notifications and domain events written in the same transaction (Task 3)
- dispatcher with SKIP LOCKED claims, retries and stale release (Task 4)
- worker building blocks: tick, LISTEN/NOTIFY wake-up, health (Task 5)
- worker process and entry points (Task 6)
- throttler counters in Postgres (Task 19)
- separate keys per purpose with key ring (Task 20)
- public origin page without exact location (Task 22)
- shop keys split into read and write (Task 23)
- Kustomize base, components, overlay encry, CI validation (Task 26)

Field capture T3 (plan 2026-10-13-t3-erfassung-am-stand), reviewed tasks:
- brood frames, read endpoints, apiary overview and offline pack
- network basics, offline queue v3, navigation sheets, form building blocks
- new inspection with last-time hints and weather, varroa per day,
  treatment prefill, apiary page with round
- inspection photo (Task 10) is implemented, review pending

Not rolled out. Remaining tasks follow in later commits.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Backend/src/varroa/varroa.controller.ts

@@ -6,13 +6,17 @@ import type { AuthenticatedUser } from '../auth/types/authenticated-user';
 import { CreateVarroaMeasurementDto } from './dto/create-varroa-measurement.dto';
 import { UpdateVarroaMeasurementDto } from './dto/update-varroa-measurement.dto';
 import { VarroaService } from './varroa.service';
+import { VarroaThresholdService } from './varroa-threshold.service';
 import { Idempotent } from '../common/idempotency/idempotent.decorator';
 
 @ApiTags('varroa-measurements')
 @ApiBearerAuth()
 @Controller('varroa-measurements')
 export class VarroaController {
-  constructor(private readonly varroaService: VarroaService) {}
+  constructor(
+    private readonly varroaService: VarroaService,
+    private readonly varroaThresholdService: VarroaThresholdService,
+  ) {}
 
   @RequirePermission('varroa:read')
   @Get()
@@ -20,6 +24,13 @@ export class VarroaController {
     return this.varroaService.findAll();
   }
 
+  /** Effective alarm threshold; declared before :id so it is not shadowed. */
+  @RequirePermission('varroa:read', 'varroa:create')
+  @Get('threshold')
+  getThreshold() {
+    return this.varroaThresholdService.current();
+  }
+
   @RequirePermission('varroa:read')
   @Get(':id')
   findOne(@Param('id') id: string) {