feat: add file logging toggle and logout confirmation

File logging defaulted to always-on meant the log grew silently on every
run with no way to turn it off. Changing the default to error-only and
exposing the toggle in Settings lets users opt in only when debugging.

The logout button previously triggered immediately without warning, making
accidental logouts unrecoverable without re-running the device code flow.
A confirmation step (Ja/Nein, gamepad-navigable) prevents that.

src/main/index.ts

@@ -9,7 +9,7 @@ import { getHlsCacheEnabled } from './prefs/hlsCachePref'
 import log from 'electron-log/main'
 
 log.initialize()
-log.transports.file.level = 'info'
+log.transports.file.level = 'error'
 log.transports.console.level = 'debug'
 
 const isDev = !app.isPackaged