feat(export): Bestandsbuch für Tierarzneimittel nach Art. 108 VO (EU) 2019/6

- Treatment records supplier, purchase proof and prescribing vet, and
  keeps the apiary the colony stood at on the treatment day.
- Holder name and address in site settings (never in public output;
  regression test in public.service.spec).
- treatment-log.pdf: one sheet per apiary, identical treatments grouped,
  missing mandatory fields printed as FEHLT, uncertain locations marked.
- Shared PDF table helpers extracted from the record card.

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

ApiCore-Backend/prisma/migrations/20260928043245_bestandsbuch_fields/migration.sql

@@ -0,0 +1,13 @@
+-- AlterTable
+ALTER TABLE "SiteSettings" ADD COLUMN     "holderAddress" TEXT,
+ADD COLUMN     "holderName" TEXT;
+
+-- AlterTable
+ALTER TABLE "Treatment" ADD COLUMN     "apiaryId" TEXT,
+ADD COLUMN     "prescribingVet" TEXT,
+ADD COLUMN     "purchaseProof" TEXT,
+ADD COLUMN     "supplier" TEXT;
+
+-- AddForeignKey
+ALTER TABLE "Treatment" ADD CONSTRAINT "Treatment_apiaryId_fkey" FOREIGN KEY ("apiaryId") REFERENCES "Apiary"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+