TCP Support

[tristanpoland]

Here we add low-level TCP support to the proxy primarily to add database support

[Copilot]

Pull Request Overview

This PR adds TCP support to Harbr-Router by introducing a new TCP proxy module, extending configuration to include TCP-specific settings, and updating the documentation to reflect these changes.

• Introduces a new TCP proxy implementation in src/tcp_proxy.rs with connection pooling and timeout handling.
• Updates the main application to conditionally launch the TCP proxy alongside the HTTP server.
• Expands configuration options and README documentation to support TCP and database proxying.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/tcp_proxy.rs	New TCP proxy module with connection pooling and bidirectional copy.
src/main.rs	Main function updated to load TCP proxy configuration and spawn a TCP proxy server.
src/config.rs	Added TCP proxy-specific configuration and helper functions.
config.yml	Extended configuration to include TCP proxy options and database routes.
README.md	Updated documentation to reflect TCP proxy support and new metrics.

Comments suppressed due to low confidence (1)

src/tcp_proxy.rs:201

• The metric name 'tcp_proxy.connection.duration' is inconsistent with the README which uses 'tcp_proxy.connection.duration_seconds'. Please standardize the metric naming for clarity.

histogram!("tcp_proxy.connection.duration", duration.as_secs_f64());