[codex] Improve UART port discovery labels

[widgetii]

What changed

• add a shared serial-port discovery layer that normalizes USB UART metadata and detects Linux aliases such as /dev/uart-*
• update the TUI port selector to show alias, raw device path, adapter identity, USB location, and serial number
• update defib ports human and JSON output to expose the same richer port identity while keeping existing JSON keys
• document that defib accepts either raw /dev/ttyUSB* paths or stable aliases like /dev/uart-orangepi5plus

Why

When multiple identical USB UART adapters are connected, the old UI only showed /dev/ttyUSB* - FT232R USB UART, which makes adapter selection ambiguous. This change keeps the existing --port contract but makes multi-adapter setups distinguishable and friendlier.

User impact

Users with simple setups can keep using /dev/ttyUSB0 exactly as before. Users with multiple adapters get much clearer labels, and Linux users who create stable /dev/uart-* symlinks will see and use those aliases automatically.

Validation

• uv run pytest tests/test_serial_ports.py tests/test_cli.py tests/test_tui.py