feat(auth): replace cookie/api-key auth with JWT Bearer tokens, separate UI from API

- Add JWT Bearer token validation to Rust API via OIDC provider JWKS
  with automatic key rotation and 1-hour cache
- Remove x-api-key auth support and built-in web UI from furumi-web-player,
  leaving it as a pure API server
- Add /auth/token endpoint to Node player server to expose OIDC access
  tokens to the frontend
- Move Node player auth endpoints from /api/* to /auth/* to avoid
  path conflicts with Rust API
- Add static file serving to Node Express server for production
  single-container deployment
- Fix SameSite=Strict cookie issue breaking OIDC redirect flow (use Lax)
- Add Dockerfile.node-player with multi-stage Node.js build
- Add CI workflows for node-player Docker image (dev + release)
- Optimize Rust Dockerfiles with dependency caching layer
- Update docker-compose with OIDC env vars and OLLAMA_MODEL support
- Cherry-pick agent LLM client fixes from DEV branch

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

furumi-agent/prompts/normalize.txt

@@ -64,7 +64,7 @@ You are a music metadata normalization assistant. Your job is to take raw metada
 
 10. **Consistency**: When the database already contains entries for an artist or album, your output MUST match the existing canonical names. Do not introduce new variations.
 
-11. **Confidence**: Rate your confidence from 0.0 to 1.0.
+11. **Confidence**: MUST be a decimal number between 0.0 and 1.0 (e.g., 0.95, 0.7, 0.3). NEVER use words like "high", "medium", "low" — only a numeric float value.
    - 1.0: All fields are clear and unambiguous.
    - 0.8+: Minor inferences made (e.g., year from path), but high certainty.
    - 0.5-0.8: Some guesswork involved, human review recommended.