Release v3.5.0: performance, constants, bilingual docs

- Bump version to 3.5.0
- Performance: hot-path timing only when log_enabled/simulate; execute_parallel takes &[Arc<SwqosClient>]; shared HTTP client constants for SWQoS
- Code quality: validate_protocol_params extracted for buy/sell; BYTES_PER_ACCOUNT, MAX_INSTRUCTIONS_WARN, HTTP timeout constants; prefetch/syscall bypass comments
- Documentation: bilingual (EN + 中文) doc comments in execution, executor, perf, swqos; README/README_CN version and What's new in 3.5.0
- Add release_notes_v3.5.0.md

Co-authored-by: Cursor <cursoragent@cursor.com>

release_notes_v3.4.1.md

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+# sol-trade-sdk v3.4.1
+
+Rust SDK for Solana DEX trading (Pump.fun, PumpSwap, Raydium, Bonk, Meteora, etc.).
+
+## What's Changed
+
+### New Features
+
+- **PumpFun & PumpSwap Cashback** (#77): Support for cashback in PumpFun and PumpSwap trading flows. See [Cashback documentation](docs/PUMP_CASHBACK_README.md).
+- **Events**: `is_cashback_coin` is now passed from events; PumpFun examples use `sol-parser-sdk` only for event parsing.
+
+### Performance
+
+- **SWQoS**: Reduced submit latency; fixed high latency after ~5 minutes idle.
+
+### Bug Fixes
+
+- **WSOL ATA**: WSOL Associated Token Account creation now runs in background with retry and timeout for more reliable setup.
+- Silenced unused and deprecated compiler warnings.
+
+### Documentation
+
+- README (EN/中文): Added Cashback section, outline, examples and tables.
+- Updated crates.io / docs references in README.
+
+---
+
+## Cargo
+
+**From Git (this release):**
+```toml
+sol-trade-sdk = { git = "https://github.com/0xfnzero/sol-trade-sdk", tag = "v3.4.1" }
+```
+
+**From crates.io** (when published):
+```toml
+sol-trade-sdk = "3.4.1"
+```
+
+**Full Changelog**: https://github.com/0xfnzero/sol-trade-sdk/compare/v3.4.0...v3.4.1