Centralize application settings UI

Signed-off-by: Loren Eteval <loren.eteval@proton.me>

Furious/Controllers/SettingsController.py

@@ -42,6 +42,10 @@ registerAppSettings(
     'ShowProgressBarWhenConnecting', isBinary=True, default=AppBinarySettings.ON_
 )
 registerAppSettings('ShowTabAndSpacesInEditor', isBinary=True)
+registerAppSettings(
+    'SystemProxyMode',
+    validRange=list(mode.value for mode in AppBuiltinProxyMode),
+)
 
 
 class SettingsController:
@@ -135,6 +139,14 @@ class SettingsController:
         cls._setBinary('ForceToLocalhostWhenSettingLocalProxy', enabled)
         showMBoxNewChangesNextTime()
 
+    @staticmethod
+    def setSystemProxyMode(mode: str):
+        """Persist how Furious manages the operating-system proxy."""
+        validModes = tuple(item.value for item in AppBuiltinProxyMode)
+
+        if mode in validModes:
+            AppSettings.set('SystemProxyMode', mode)
+
     @classmethod
     def setAutoUpdateAssets(cls, enabled: bool):
         """Persist automatic core-asset updates."""