fix: move blob migration server-side, restore lightweight list loading

The client-side migration was downloading 25-50MB of base64 data to the
browser before showing anything. getAllEntries also lost its lightweight flag.

Fix:
- New POST /api/storage/migrate-blobs endpoint runs entirely server-side
  (loads entries one-at-a-time from PostgreSQL, never sends heavy data to browser)
- Restore lightweight:true on getAllEntries (strips remaining base64 in API)
- Migration fires on mount (fire-and-forget) while list loads independently
- Remove client-side migrateEntryBlobs function

src/modules/registratura/hooks/use-registry.ts

@@ -17,7 +17,6 @@ import {
   saveEntry,
   deleteEntry,
   generateRegistryNumber,
-  migrateEntryBlobs,
 } from "../services/registry-service";
 import {
   createTrackedDeadline,
@@ -54,18 +53,19 @@ export function useRegistry() {
     setLoading(false);
   }, [storage]);
 
-  // On mount: run migration (once), then load entries
+  // On mount: trigger server-side blob migration (fire-and-forget), then load list
   // eslint-disable-next-line react-hooks/set-state-in-effect
   useEffect(() => {
     const init = async () => {
+      // Trigger server-side migration (runs inside Node.js, not browser)
       if (!migrationRan.current) {
         migrationRan.current = true;
-        await migrateEntryBlobs(storage, blobStorage);
+        fetch("/api/storage/migrate-blobs", { method: "POST" }).catch(() => {});
       }
       await refresh();
     };
     init();
-  }, [refresh, storage, blobStorage]);
+  }, [refresh]);
 
   const addEntry = useCallback(
     async (