fix: URL-length-aware OpenAlex batching and eager scholar metadata hydration

- Replace fixed batch_size=25 with URL-byte-length-aware chunking for
  OpenAlex title.search queries. Long/Unicode titles caused URLs to
  exceed server limits, resulting in 500 errors.
- Always hydrate scholar profile metadata (name, image) on creation,
  even when an initial scrape job is queued, so the UI shows profile
  info immediately.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/api/routers/scholars.py

@@ -144,18 +144,17 @@ async def create_scholar(
             message=str(exc),
         ) from exc
     structured_log(logger, "info", "api.scholars.created", user_id=current_user.id, scholar_profile_id=created.id)
-    did_queue_initial_scrape = await enqueue_initial_scrape_job_for_scholar(
+    await enqueue_initial_scrape_job_for_scholar(
         db_session,
         profile=created,
         user_id=current_user.id,
     )
-    if not did_queue_initial_scrape:
-        created = await hydrate_scholar_metadata_if_needed(
-            db_session,
-            profile=created,
-            source=source,
-            user_id=current_user.id,
-        )
+    created = await hydrate_scholar_metadata_if_needed(
+        db_session,
+        profile=created,
+        source=source,
+        user_id=current_user.id,
+    )
 
     return success_payload(
         request,