feat(search): pass pro_user flag through indexer search_v3 method

Enables Cohere reranking for pro users only

Author: DevanshuNEU

backend/services/indexer_optimized.py

@@ -574,14 +574,18 @@ async def search_v3(
         top_k: int = 10,
         include_tests: bool = False,
         use_reranking: bool = True,
+        pro_user: bool = False,
     ) -> List[Dict]:
         """
         Search V3 - "Project Brain" search with:
         - Voyage AI code-optimized embeddings (if available)
         - Query understanding & intent classification
         - Code graph importance ranking
         - Test file filtering
-        - Cohere reranking
+        - Cohere reranking (pro users only)
+        
+        Args:
+            pro_user: Enable Cohere reranking (costs money, pro tier only)
         """
         from services.search_v3.integration import get_search_v3
 
@@ -609,7 +613,8 @@ async def search_v3(
                 file_dependencies=file_dependencies,
                 include_tests=include_tests,
                 top_k=top_k,
-                use_reranking=use_reranking
+                use_reranking=use_reranking,
+                pro_user=pro_user
             )
 
             elapsed = time.time() - start_time