feat: store node logo/favicon in postgres instead of S3

- Add logoData and faviconData columns to nodes table
- Create /api/admin/node/upload endpoint for direct DB storage
- Create /api/node/logo and /api/node/favicon endpoints to serve images
- Update admin page to use new upload endpoint
- Remove dependency on admin's personal S3 storage for node assets

src/lib/auth/index.ts

@@ -200,7 +200,7 @@ export async function registerUser(
     const fullHandle = `${handle.toLowerCase()}@${nodeDomain}`;
     const avatarUrl = await generateAndUploadAvatarToUserStorage(
         fullHandle,
-        storageEndpoint || null,
+        storageEndpoint || undefined,
         storageRegion,
         storageBucket,
         storageAccessKey,