fix(web): zwei tsc-Buildfehler (useMutation-Rueckgabe void, Uint8Array<ArrayBuffer>)

Blockierten den CI-Frontend-Build (npm run build) und damit build-and-push.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gerbil-manager-web/src/components/GerbilAcquisitionSection.tsx

@@ -32,14 +32,15 @@ export default function GerbilAcquisitionSection({ gerbilId }: { gerbilId: strin
   const [note, setNote] = useState('')
   const [error, setError] = useState<string | null>(null)
 
-  const save = useMutation((id: string | '') => {
+  const save = useMutation(async (id: string | '') => {
     const body = {
       gerbilId,
       date: date || null,
       price: price.trim() === '' ? null : Number(price),
       note: note.trim() || null,
     }
-    return id === '' ? createAcquisition(body) : updateAcquisition(id, body)
+    if (id === '') await createAcquisition(body)
+    else await updateAcquisition(id, body)
   })
   const removal = useMutation((id: string) => deleteAcquisition(id))
 

gerbil-manager-web/src/push.ts

@@ -25,7 +25,7 @@ export async function fetchPushConfig(): Promise<{ enabled: boolean; publicKey:
   }
 }
 
-function urlBase64ToUint8Array(base64: string): Uint8Array {
+function urlBase64ToUint8Array(base64: string): Uint8Array<ArrayBuffer> {
   const padding = '='.repeat((4 - (base64.length % 4)) % 4)
   const b64 = (base64 + padding).replace(/-/g, '+').replace(/_/g, '/')
   const raw = atob(b64)