feat(agent): switch LLM client from Ollama to OpenAI-compatible API (LM Studio support)

- Replace /api/chat with /v1/chat/completions endpoint
- Use json_schema response_format (LM Studio does not support json_object)
- Make schema parameter optional in call_ollama to support different schemas per use case
- Add dedicated normalize schema (normalized_metadata) with release_kind field
  instead of release_type to avoid model repetition loops
- Add dedicated merge schema (artist_merge) so model no longer confuses
  normalize and merge response structures
- Add retry with frequency_penalty=1.5 on parse failure to suppress repetition
- Add id3 crate as fallback metadata reader for MP3 files with large embedded
  cover art that exceed Symphonia probe limit of 1MB

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -1191,6 +1191,7 @@ dependencies = [
  "tokio",
  "tokio-util",
  "tower 0.4.13",
+ "tower-http",
  "tracing",
  "tracing-subscriber",
  "urlencoding",