iron_runtime 0.4.0

# Directory: llm_router

## Responsibility Table

| File | Responsibility |
|------|----------------|
| error.rs | Defines LLM router error types |
| key_fetcher.rs | Fetches provider API keys from server |
| mod.rs | Exports LLM router module public API |
| proxy.rs | Implements local HTTP proxy server |
| router.rs | Provides PyO3 class for Python integration |

## Validation

One-Second Test: Scan the Responsibility column - if any two entries sound similar, they overlap and must be reconsolidated.