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/transport/middle_proxy/registry.rs

@@ -165,6 +165,7 @@ impl ConnRegistry {
         None
     }
 
+    #[allow(dead_code)]
     pub async fn route(&self, id: u64, resp: MeResponse) -> RouteResult {
         let tx = {
             let inner = self.inner.read().await;
@@ -438,6 +439,7 @@ impl ConnRegistry {
             .unwrap_or(true)
     }
 
+    #[allow(dead_code)]
     pub async fn unregister_writer_if_empty(&self, writer_id: u64) -> bool {
         let mut inner = self.inner.write().await;
         let Some(conn_ids) = inner.conns_for_writer.get(&writer_id) else {