fix(scholars): improve validation, fix delete, add status badges

- Extract scholar ID parsing to dedicated module with robust URL
  handling (trailing slashes, fragments, extra query params, encoded
  characters) and per-token error feedback showing why each invalid
  entry was skipped
- Wrap delete_scholar DB commit in IntegrityError handler so cascade
  failures return a proper API error instead of 500
- Add ScholarStatusBadges component showing Pending/Failed/Partial/OK
  badges on scholar rows based on baseline_completed and last_run_status
- Show Pending badge in ScholarSettingsModal for unscraped scholars
- Surface failed_count and partial_count in dashboard latest run summary
  and recent run list items
- Extend backend validator tests with edge cases (empty, whitespace,
  unicode, URL-as-ID)
- Add integration tests for DELETE 404, DELETE with cascade, and POST
  with corrupted scholar_id
- Add comprehensive frontend tests for parsing logic and component
  behavior

app/services/scholars/application.py

@@ -125,7 +125,11 @@ async def delete_scholar(
         _safe_remove_upload(upload_root, profile.profile_image_upload_path)
 
     await db_session.delete(profile)
-    await db_session.commit()
+    try:
+        await db_session.commit()
+    except IntegrityError as exc:
+        await db_session.rollback()
+        raise ScholarServiceError("Unable to delete scholar due to a database constraint.") from exc
 
 
 async def hydrate_profile_metadata(