- Implemented gRPC-based tunnel sessions for multiplexing HTTP requests via `grpcTunnelSession` with features like `recvLoop`, `send`, and per-stream state management.
- Registered and unregistered tunnels for domains, replacing DTLS-based sessions for improved scalability and maintainability.
- Integrated domain validation checks during gRPC tunnel handshake with configurable validator support.
- Modified static error pages (`400.html`, `404.html`, `502.html`, `504.html`, `500.html`, `525.html`) to include favicon linking, enhancing error page presentation.
- Introduced handling for `502 Bad Gateway` errors with a dedicated HTML template.
- Updated `writeErrorPage` logic to include 502 and other new status mappings for custom templates.
- Improved error page rendering by mapping 4xx/5xx status codes to appropriate templates.
- Introduced `StatusGatewayTimeout` (504) for server-side timeouts between HopGate and backend.
- Implemented 504 error page with multilingual support.
- Enhanced `bufio.Reader` usage in JSON decoding to prevent "dtls: buffer too small" errors for large payloads.
- Applied request handling improvements for control domain and timeout scenarios.
- Updated error templates (`400`, `404`, `500`, `525`) to apply consistent width (`w-[240px]`) for the HopGate logo.
- Adjusted Tailwind CSS to include the new `w-[240px]` class for accurate rendering.
- Implemented custom HTML templates for `400`, `404`, `500`, and `525` error pages with multilingual support.
- Added embedded file system for error page templates and assets.
- Introduced fallback mechanism to serve minimal plain text for missing error templates.
- Integrated TailwindCSS for styling error pages, with a build script in `package.json`.
