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);

products/01-llm-cost-router/src/worker/digest.rs

@@ -177,7 +177,7 @@ async fn generate_digest(ts_pool: &PgPool, org_id: Uuid, org_name: &str) -> anyh
     let savings_pct = if summary.1 > 0.0 { (summary.3 / summary.1) * 100.0 } else { 0.0 };
 
     Ok(DigestData {
-        org_id,
+        _org_id: org_id,
         org_name: org_name.to_string(),
         total_requests: summary.0,
         total_cost_original: summary.1,
@@ -201,6 +201,7 @@ async fn generate_digest(ts_pool: &PgPool, org_id: Uuid, org_name: &str) -> anyh
 #[cfg(test)]
 mod tests {
     use super::*;
+    use chrono::Weekday;
 
     #[test]
     fn next_monday_from_wednesday() {