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

src/trading/core/executor.rs

@@ -129,6 +129,7 @@ impl TradeExecutor for GenericTradeExecutor {
             if is_buy { true } else { params.with_tip },
             params.gas_fee_strategy,
             params.use_core_affinity,
+            params.check_min_tip,
         )
         .await;
         let send_elapsed = send_start.map(|s| s.elapsed()).unwrap_or(Duration::ZERO);