fix(harvests): allow several harvests of the same type per year

The ApiCore sync failed with "Unique constraint failed on the constraint:
harvests_year_type_key" as soon as ApiCore had two harvests of the same
honey type in one year, which is normal (several extractions per season).
Every bottling of that harvest was then skipped too.

- Drop the (year, type) unique index. The slug is now the only unique,
  public identifier: /ernten/<slug>, e.g. bluetenhonig-2026, then
  bluetenhonig-2026-07-14 for a further harvest of the same type.
- New Harvest.apicoreHarvestId as the sync key, backfilled from the old
  "apicore-<id>" slugs; the sync gives those rows a readable slug.
- Slugs are generated by one shared slugify() that normalizes Unicode
  (decomposed umlauts) and writes out umlauts. The migration repairs
  manual slugs created by the old umlaut bug ("fr-htracht-2026").
- Slug collisions are resolved by the database unique index, so parallel
  writers cannot produce duplicates; known slugs are skipped up front to
  keep the logs free of handled P2002 errors.
- Old URLs /ernten/<year>/<type> answer with 308 to the new address.

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

src/app/admin/actions/harvests-batches.ts

@@ -6,6 +6,8 @@ import { logAdminAction } from "@/lib/audit-log";
 import { isValidUploadPath } from "@/lib/uploads";
 import { requireAdmin, fail, str, num, strArraySlots } from "./_shared";
 import { succeed } from "@/lib/flash";
+import { harvestSlugCandidates, writeWithFreeSlug } from "@/lib/harvest-slug";
+import { findTakenHarvestSlugs } from "@/lib/harvest-slug-db";
 
 /**
  * Bildslots fuer Ernte und Charge. Die Position entscheidet, WELCHE Kachel
@@ -26,25 +28,33 @@ export async function createHarvestAction(formData: FormData): Promise<void> {
   const admin = await requireAdmin();
   const year = num(formData, "year");
   const type = str(formData, "type");
-  const slug = `${type.toLowerCase().replace(/[^a-z0-9]+/g, "-")}-${year}`;
+  const harvestDate = new Date(str(formData, "harvestDate"));
+  if (!type || !Number.isInteger(year) || year < 1 || Number.isNaN(harvestDate.getTime())) {
+    return fail("/admin/ernten", "Bitte Sorte, Jahr und ein gültiges Erntedatum angeben.");
+  }
   // Checkbox: nur in formData vorhanden, wenn angehakt — fehlt sie ganz
   // (kein Feld im Formular), gilt "veroeffentlicht" als sicherer Default fuer
   // manuell im Admin-Bereich angelegte Ernten (bisheriges Verhalten vor
   // Einfuehrung von isPublished).
   const isPublished = !formData.has("isPublished") || formData.get("isPublished") === "on";
 
-  const harvest = await prisma.harvest.create({
-    data: {
-      year,
-      type,
-      slug,
-      harvestDate: new Date(str(formData, "harvestDate")),
-      location: str(formData, "location") || "Altenmünster",
-      description: str(formData, "description"),
-      images: imageSlots(formData),
-      isPublished,
-    },
-  });
+  // Dieselbe Sorte darf mehrmals im Jahr geerntet werden; die zweite bekommt
+  // eine Adresse mit Erntedatum statt eines Fehlers (lib/harvest-slug.ts).
+  const harvest = await writeWithFreeSlug(harvestSlugCandidates(type, harvestDate), (slug) =>
+    prisma.harvest.create({
+      data: {
+        year,
+        type,
+        slug,
+        harvestDate,
+        location: str(formData, "location") || "Altenmünster",
+        description: str(formData, "description"),
+        images: imageSlots(formData),
+        isPublished,
+      },
+    }),
+    findTakenHarvestSlugs
+  );
 
   await logAdminAction(admin, {
     action: "harvest.create",