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>

.gitignore

@@ -1,30 +1,12 @@
-# Generated by Cargo
-# will have compiled files and executables
-debug/
-target/
+# Proto 生成工具和生成的代码（用户不需要）
+/proto/gen/
 
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
-# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+# 预生成的 proto Rust 代码（提交到仓库，但用户不应修改）
+# /src/swqos/pb/serverpb.rs  <- 这个文件已经提交，用户不应修改
+
+# Build artifacts
+/target/
 Cargo.lock
 
-# These are backup files generated by rustfmt
-**/*.rs.bk
-
-# MSVC Windows builds of rustc generate these, which store debugging information
-*.pdb
-
-# RustRover
-#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
-#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
-#  and can be added to the global gitignore or merged into this file.  For a more nuclear
-#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
-#.idea/
-
-.cargo/
-
-tmp_*.rs
-tmp_*.log
-
-
-.claude/
-.serena/
+# Proto sources
+/proto/