## Description
Adds optional TLS support for the AI Bridge Proxy listener. When TLS cert and key files are provided, the proxy serves over HTTPS instead of plain HTTP.
## Changes
* New configuration options to enable TLS on the proxy listener
* Wraps the TCP listener in `tls.NewListener` when configured
* Tests for validation errors, invalid files, and full integration (tunneled + MITM) through a TLS listener
Note: Documentation for TLS listener setup and client configuration will be handled in a follow-up PR.
Related to: https://github.com/coder/internal/issues/1335