feat: Helius Sender SWQOS support and global check_min_tip option

- Add Helius Sender client (helius.rs) with dual routing and swqos_only mode
- Helius min tip: 0.0002 SOL default, 0.000005 SOL when swqos_only=true
- Add TradeConfig.check_min_tip (default false) to skip min-tip validation for lower latency
- Thread check_min_tip through SwapParams and execute_parallel; only call min_tip_sol when enabled
- Add SWQOS_ENDPOINTS_HELIUS and HELIUS_TIP_ACCOUNTS in constants
- Extend SwqosConfig/SwqosType for Helius; add Helius to get_endpoint and get_swqos_client
- Update trading_client, shared_infrastructure and middleware_system examples

Made-with: Cursor

examples/shared_infrastructure/src/main.rs

@@ -31,6 +31,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         SwqosConfig::Default(rpc_url.clone()),
         SwqosConfig::Jito("your_uuid".to_string(), SwqosRegion::Frankfurt, None),
         SwqosConfig::Bloxroute("your_api_token".to_string(), SwqosRegion::Frankfurt, None),
+        SwqosConfig::Helius("".to_string(), SwqosRegion::Default, None, Some(true)),
     ];
 
     // Step 1: Create shared infrastructure (expensive, do once)