feat: score-based search, LLM re-ranking endpoint, video title search, pipeline module

Core search changes:
- Replace RRF with score-based merge (max of semantic/keyword/identity)
- Add video title ILIKE search for brand/name queries (score 0.9)
- Add /api/v1/search/llm-smart endpoint with Gemma 4 re-ranking
- Fix LLM JSON parsing (markdown fences, empty responses)

Infrastructure:
- Rebuild Qdrant collection (clear 347K contaminated points)
- Add dotenv loading to main.rs for config parity
- Implement store_pre_chunk in postgres_db.rs

Pipeline module (WordPress):
- store-asrx, rule1, vectorize, phase1, complete endpoints
- CLI commands for pipeline operations

Docs:
- SEARCH_SCORE_IMPROVEMENT.md (score-based merge proposal)

src/api/mod.rs

@@ -9,8 +9,10 @@ pub mod identities;
 pub mod identity_agent_api;
 pub mod identity_api;
 pub mod identity_binding;
+pub mod llm_search;
 pub mod media_api;
 pub mod middleware;
+pub mod pipeline;
 pub mod processing;
 pub mod scan;
 pub mod search;