Fix CI workflow: use correct rust-toolchain action (#1)

* Fix CI workflow: use correct rust-toolchain action

* Fix CI: resolve Rust compilation and formatting issues
- Fix rust-toolchain action name in CI workflow
- Add missing Direction import in test modules
- Add missing entry_fees argument to open_position test calls
- Comment out nightly-only rustfmt options
- Auto-format code with cargo fmt

src/execution/fees.rs

@@ -92,10 +92,7 @@ pub struct BrokerFees;
 impl BrokerFees {
     /// Interactive Brokers tiered pricing (approximate).
     pub fn interactive_brokers() -> FeeModel {
-        FeeModel::Custom {
-            base: 1.0,
-            per_share: 0.005,
-        }
+        FeeModel::Custom { base: 1.0, per_share: 0.005 }
     }
 
     /// Zero commission broker (like Robinhood).