Refactor proxy and transport modules for improved safety and performance

- Enhanced linting rules in `src/proxy/mod.rs` to enforce stricter code quality checks in production.
- Updated hash functions in `src/proxy/middle_relay.rs` for better efficiency.
- Added new security tests in `src/proxy/tests/middle_relay_stub_completion_security_tests.rs` to validate desynchronization behavior.
- Removed ignored test stubs in `src/proxy/tests/middle_relay_security_tests.rs` to clean up the test suite.
- Improved error handling and code readability in various transport modules, including `src/transport/middle_proxy/config_updater.rs` and `src/transport/middle_proxy/pool.rs`.
- Introduced new padding functions in `src/stream/frame_stream_padding_security_tests.rs` to ensure consistent behavior across different implementations.
- Adjusted TLS stream validation in `src/stream/tls_stream.rs` for better boundary checking.
- General code cleanup and dead code elimination across multiple files to enhance maintainability.

src/stream/tls_stream.rs

@@ -154,7 +154,7 @@ impl TlsRecordHeader {
             }
 
             TLS_RECORD_HANDSHAKE => {
-                if len < 4 || len > MAX_TLS_PLAINTEXT_SIZE {
+                if !(4..=MAX_TLS_PLAINTEXT_SIZE).contains(&len) {
                     return Err(Error::new(
                         ErrorKind::InvalidData,
                         format!(