Summary by cubic

Fixes base URL overrides for agent LLM calls. Preset/preset-configured base_url now reliably overrides workspace credential base URLs, with optional base URLs supported for OpenAI and Anthropic.

• Bug Fixes
  • Propagate base_url through LLM tokens and gateway metadata; durable workflow passes cfg.base_url to mint_llm_token.
  • Inject api_base from OPENAI_BASE_URL/ANTHROPIC_BASE_URL when present, then prefer token/preset base_url for openai, anthropic, and custom-model-provider.
  • Added unit tests for injection and override precedence.

^{Written for commit b5de519. Summary will update on new commits.}