fix(CF-1316): Use LiteLLM model alias claude-haiku-4.5

The full Anthropic model ID is not registered in LiteLLM.
Use the LiteLLM alias instead.

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

.env.example

@@ -9,7 +9,7 @@ LLM_API_URL=https://api.agiliton.cloud/llm
 LLM_API_KEY=your_llm_api_key_here
 
 # LLM metadata extraction at embedding time (CF-1316)
-METADATA_EXTRACTION_MODEL=claude-haiku-4-5-20251001
+METADATA_EXTRACTION_MODEL=claude-haiku-4.5
 
 # Cross-encoder re-ranking (CF-1317)
 RERANK_ENABLED=false