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/lib/apicore-mapping.test.ts

@@ -1,7 +1,7 @@
 import { describe, test, expect } from "vitest";
 import { isSellableStatus, type ApiCoreProduct, type ApiCoreHarvest } from "./apicore-client";
 import {
-  slugForApiCoreSource,
+  hasLegacyApiCoreSlug,
   buildHarvestDescription,
   buildProductDescription,
   deriveWeightGrams,
@@ -40,25 +40,13 @@ function makeHarvest(overrides: Partial<ApiCoreHarvest> = {}): ApiCoreHarvest {
   };
 }
 
-describe("slugForApiCoreSource", () => {
-  test("leitet den Slug ausschliesslich aus der ApiCore-ID ab", () => {
-    // Arrange
-    const sourceId = "cm-product-1";
-
-    // Act
-    const slug = slugForApiCoreSource(sourceId);
-
-    // Assert
-    expect(slug).toBe("apicore-cm-product-1");
+describe("hasLegacyApiCoreSlug", () => {
+  test("erkennt das alte Slug-Format 'apicore-<ID>'", () => {
+    expect(hasLegacyApiCoreSlug("apicore-cmtx1ri7x001j012bvcqh9tpt")).toBe(true);
   });
 
-  test("bleibt stabil, wenn sich in ApiCore nur der Name aendert", () => {
-    // Arrange: derselbe Datensatz, in ApiCore umbenannt.
-    const before = makeProduct({ name: "Sommertracht 500 g" });
-    const after = makeProduct({ name: "Sommertracht cremig, 500 g" });
-
-    // Act & Assert: sonst wuerde der Sync ein zweites Produkt anlegen.
-    expect(slugForApiCoreSource(after.id)).toBe(slugForApiCoreSource(before.id));
+  test("laesst lesbare Adressen in Ruhe", () => {
+    expect(hasLegacyApiCoreSlug("bluetenhonig-2026")).toBe(false);
   });
 });