Add config.LoadFrom/SaveTo for arbitrary paths and thread a --config
flag through both entry points:
- CLI: --config loads a file first; explicit flags override file values
- GUI: --config selects the settings file used for load and save
- tests for LoadFrom/SaveTo and default fallback
- internal/gui: settings form (name, port, source, quality, fps, audio)
wired to the flinger engine, config save/load, start/stop toggle
- system tray via Fyne's StatusNotifierItem: Show (raises window),
Start/Stop, Quit; left-click shows the settings window
- cmd/teleportfling-gui entry point
Verified on Hyprland: tray icon registers, start/stop streaming works,
window shows and focuses from the tray.
petere