feat(tier): Erwerb/Kauf je Tier (Datum, Preis, Notiz)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

gerbil-manager-web/e2e/mock-api.ts

@@ -416,6 +416,50 @@ export async function installMockApi(page: Page): Promise<MockDb> {
       return json(route, 405)
     }
 
+    // ERWERB: Erwerb/Kauf je Tier — GET ?gerbilId= (Array, kein Gridify-Paging),
+    // POST/PUT/DELETE. Vor den generischen Kollektionen, weil GET kein {items}-Objekt
+    // liefert und nach gerbilId statt Gridify-filter selektiert.
+    const acqMatch = path.match(/^\/acquisitions(?:\/([^/]+))?$/)
+    if (acqMatch) {
+      const acqId = acqMatch[1] ? decodeURIComponent(acqMatch[1]) : null
+      if (!acqId) {
+        if (method === 'GET') {
+          const gid = url.searchParams.get('gerbilId')
+          const rows = db.acquisitions.filter((a) => !gid || a.gerbilId === gid)
+          return json(route, 200, [...rows].reverse())
+        }
+        if (method === 'POST') {
+          const created = {
+            id: newId('acq'),
+            sourceContactId: null,
+            date: null,
+            price: null,
+            note: null,
+            ...(request.postDataJSON() as Row),
+            createdAt: new Date().toISOString(),
+          }
+          db.acquisitions.push(created)
+          return json(route, 201, created)
+        }
+        return json(route, 405)
+      }
+      const ai = db.acquisitions.findIndex((a) => a.id === acqId)
+      if (method === 'GET') {
+        return ai >= 0 ? json(route, 200, db.acquisitions[ai]) : json(route, 404, { title: 'Not Found' })
+      }
+      if (method === 'PUT') {
+        if (ai < 0) return json(route, 404, { title: 'Not Found' })
+        Object.assign(db.acquisitions[ai], request.postDataJSON() as Row)
+        return json(route, 204)
+      }
+      if (method === 'DELETE') {
+        if (ai < 0) return json(route, 404, { title: 'Not Found' })
+        db.acquisitions.splice(ai, 1)
+        return json(route, 204)
+      }
+      return json(route, 405)
+    }
+
     // Generische Kollektionen: /<resource> und /<resource>/<id>
     m = path.match(/^\/([a-z-]+)(?:\/([^/]+))?$/)
     const col = m ? collections[m[1]] : undefined