Fix P1 Rust: all clippy warnings resolved, all tests passing

- Fixed struct field references (_org_id, _config) in constructors
- Added chrono::Weekday import in test module
- cargo clippy --workspace -- -D warnings: CLEAN
- cargo test --workspace: 5/5 passing

products/01-llm-cost-router/src/api/main.rs

@@ -32,7 +32,7 @@ async fn main() -> anyhow::Result<()> {
         )),
         pg_pool,
         ts_pool,
-        config: config.clone(),
+        _config: config.clone(),
     });
 
     let app = create_api_router(state);