Release v4.0.0: SWQoS transport improvements and Binary-Tx response handling

Major changes:
- Switch BlockRazor default transport from gRPC to HTTP to avoid FRAME_SIZE_ERROR
  - gRPC mode still available via explicit SwqosTransport configuration
- Fix ZeroSlot Binary-Tx JSON-RPC 2.0 response parsing
  - Properly handle success responses with "result" field
  - Properly handle error responses with "error" field containing code and message
- Update version to 4.0.0
- Update README files to reflect new version

Technical details:
- BlockRazor: HTTP mode is now the default (SwqosTransport::Http or None)
- ZeroSlot: Parse JSON-RPC 2.0 format responses instead of plain text
- Proto code: Pre-generated gRPC code for BlockRazor (no protoc required)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sol-trade-sdk"
-version = "3.6.5"
+version = "4.0.0"
 edition = "2021"
 authors = [
     "William <byteblock6@gmail.com>",
@@ -135,6 +135,10 @@ incremental = true         # 增量编译 - 大幅加速重新编译
 opt-level = 1              # 开发时适度优化
 overflow-checks = true     # 开发时启用溢出检查
 
+# 🚀 构建依赖
+# 注意：proto 代码已预生成在 src/swqos/pb/serverpb.rs
+# 开发者如需重新生成代码，请运行 gen_proto 目录下的工具
+
 # 🚀 性能关键依赖的特殊优化
 [profile.release.package.solana-sdk]
 opt-level = 3