Configuration Boundary

We keep configuration loading at the application edge and core code configuration‑agnostic.

• Core main code must not read configuration directly. All PureConfig/env/system property access lives only in org.llm4s.config; everywhere else consumes typed settings injected from the application edge.
• Llm4sConfig is for edge use (samples, CLIs, tests). Core main sources should not reference it.
• Scalafix enforces this: in modules/core/src/main/scala, imports/uses of Llm4sConfig, ConfigSource.default, sys.env, or System.getenv are blocked (except inside org.llm4s.config). Tests and runnable mains are exempt.
• To pass configuration into core, load it at the edge (e.g., via Llm4sConfig) and inject the typed settings into your builders/factories.