feat: refactor trade API to return execution status with signature

- Bump version from 1.2.0 to 1.2.1
- Change trade methods return type from Signature to (bool, Signature)
- Improve parallel execution error handling and status tracking
- Update CLI examples to match new API interface
- Enhance transaction success/failure reporting capabilities

Breaking Change: Trade API now returns tuple (success_status, signature)

README.md

@@ -87,14 +87,14 @@ Add the dependency to your `Cargo.toml`:
 
 ```toml
 # Add to your Cargo.toml
-sol-trade-sdk = { path = "./sol-trade-sdk", version = "1.2.0" }
+sol-trade-sdk = { path = "./sol-trade-sdk", version = "1.2.1" }
 ```
 
 ### Use crates.io
 
 ```toml
 # Add to your Cargo.toml
-sol-trade-sdk = "1.2.0"
+sol-trade-sdk = "1.2.1"
 ```
 
 ## 🛠️ Usage Examples