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/params.rs

@@ -71,6 +71,8 @@ pub struct SwapParams {
     pub log_enabled: bool,
     /// Whether to pin parallel submit tasks to cores (from TradeConfig.use_core_affinity).
     pub use_core_affinity: bool,
+    /// Whether to check minimum tip per SWQOS (from TradeConfig.check_min_tip). When false, skip filter for lower latency.
+    pub check_min_tip: bool,
     /// Optional event receive time in microseconds (same scale as sol-parser-sdk clock::now_micros). Used as timing start when log_enabled.
     pub grpc_recv_us: Option<i64>,
     /// Use exact SOL amount instructions (buy_exact_sol_in for PumpFun, buy_exact_quote_in for PumpSwap).