- **KCP/WebRTC UDP Port Multiplexing**: All protocols (HTTP, HTTPS, W…

…SS, SSH, WebRTC, KCP) now share a single configurable port. KCP no longer requires a separate port (tcp_port+1). This simplifies firewall configuration — only one port needs to be open.

- **Logging System Overhaul**: Replaced env_logger with tracing-subscriber + tracing-appender.
  - Server: fixed filename with daily log rotation (max 7 files)
  - Client/Shell: PID-based filenames with automatic cleanup of old logs (max 10 files, 7 days retention)
  - Reduced log noise: SessionUpdate/ClientSetTitle downgraded from info to debug level

- Server now uses a single port for all protocols. Clients should connect to the same port as the server's listen address (no longer port+1 for KCP).

Fix CI warnings and update README

- Fix SERVICE_NAME unused warning on macOS (use cfg instead of allow(dead_code))
- Fix run() unused warning on FreeBSD/Windows (add cfg gate)
- Fix cargo fmt check failure from long cfg_attr line
- Prepend saw-shell config to beginning of RC files
- Add brew install instruction for macOS in README
- Remove root/admin comment from saw-server install

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>