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/test/treatments.e2e-spec.ts

@@ -254,4 +254,100 @@ describe('Treatments (e2e)', () => {
           .expect(400),
     );
   });
+
+  describe('GET /treatments/last-by-product', () => {
+    const productName = `Oxuvar-${Date.now()}`;
+
+    const lastByProduct = (token: string, product?: string) =>
+      request(app.getHttpServer())
+        .get('/api/v1/treatments/last-by-product')
+        .query(product === undefined ? {} : { product })
+        .set('Authorization', `Bearer ${token}`);
+
+    beforeAll(async () => {
+      await prisma.treatment.createMany({
+        data: [
+          {
+            colonyId,
+            userId: beekeeperId,
+            date: new Date('2026-05-01T00:00:00.000Z'),
+            product: productName,
+            supplier: 'Alt GmbH',
+          },
+          {
+            colonyId,
+            userId: beekeeperId,
+            date: new Date('2026-06-01T00:00:00.000Z'),
+            product: productName,
+            activeIngredient: 'Oxalsäure',
+            withdrawalPeriodDays: 0,
+            supplier: 'Neu GmbH',
+            purchaseProof: 'RE-2026-17',
+            prescribingVet: 'Dr. Imker',
+          },
+          {
+            colonyId,
+            userId: staffId,
+            date: new Date('2026-07-01T00:00:00.000Z'),
+            product: productName,
+            supplier: 'Fremd GmbH',
+          },
+        ],
+      });
+    });
+
+    it("returns the caller's newest treatment with that product, case-insensitive", async () => {
+      const response = await lastByProduct(
+        beekeeperToken,
+        ` ${productName.toLowerCase()} `,
+      ).expect(200);
+      const newest = await prisma.treatment.findFirstOrThrow({
+        where: {
+          userId: beekeeperId,
+          product: productName,
+          supplier: 'Neu GmbH',
+        },
+        select: { id: true },
+      });
+
+      expect(response.body).toEqual({
+        treatment: {
+          sourceTreatmentId: newest.id,
+          sourceDate: '2026-06-01T00:00:00.000Z',
+          product: productName,
+          activeIngredient: 'Oxalsäure',
+          withdrawalPeriodDays: 0,
+          supplier: 'Neu GmbH',
+          purchaseProof: 'RE-2026-17',
+          prescribingVet: 'Dr. Imker',
+        },
+      });
+    });
+
+    it("never returns another user's treatment", async () => {
+      const response = await lastByProduct(beekeeperToken, productName).expect(
+        200,
+      );
+
+      expect(JSON.stringify(response.body)).not.toContain('Fremd GmbH');
+    });
+
+    it('returns { treatment: null } without a match', async () => {
+      const response = await lastByProduct(
+        beekeeperToken,
+        `Unbekannt-${Date.now()}`,
+      ).expect(200);
+
+      expect(response.body).toEqual({ treatment: null });
+    });
+
+    it('rejects a request without product', () =>
+      lastByProduct(beekeeperToken).expect(400));
+
+    it('rejects an empty product', () =>
+      lastByProduct(beekeeperToken, '   ').expect(400));
+
+    it('rejects a role without treatments:create', () =>
+      lastByProduct(staffToken, productName).expect(403));
+  });
 });