`build_ui` (the GTK `activate` handler) started a fresh SDL3 gamepad
worker thread on every reactivation of the already-running singleton
(another --connect, the launcher clicked twice, ...). sdl3 only lets
the first thread ever to call sdl3::init() hold "main thread" status,
so every later activation's worker thread failed permanently with
"Cannot initialize `Sdl` from a thread other than the main thread",
silently disabling controller support for the rest of the process.
Start the GamepadService once in run() and clone it into build_ui
instead of starting a new one per activation.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
enricobuehler
7b4132f74b