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/trading_client/src/main.rs

@@ -49,6 +49,8 @@ async fn create_trading_client_simple() -> AnyResult<TradingClient> {
         SwqosConfig::Node1("your_api_token".to_string(), SwqosRegion::Frankfurt, None),
         SwqosConfig::BlockRazor("your_api_token".to_string(), SwqosRegion::Frankfurt, None),
         SwqosConfig::Astralane("your_api_token".to_string(), SwqosRegion::Frankfurt, None),
+        // Helius Sender: 4th param swqos_only Some(true) => min tip 0.000005 SOL; None => 0.0002 SOL
+        SwqosConfig::Helius("".to_string(), SwqosRegion::Default, None, Some(true)),
     ];
 
     // Optional: Customize WSOL ATA and Seed optimization settings