Config presets now run after the toml loads: the ac6_fix_* switches and
their scale gates finally honor user settings. The settings save persists
only user-set values, with toml escaping - no leaked presets, and a saved
Windows path can no longer void the whole config. Runtime-forced values
(performance mode) can no longer overwrite the user's saved choices.
Menu: wrapped tooltips, "(set by <cvar>)" on driven entries, a developer
toggle; AC6-added cvars grouped under the AC6 node as AC6/Fixes and
AC6/Enhancements, with true restart/live lifecycles.
Dipshet