fix(internal): add usingLua to HyprExtras for idle action gating

[Mestane]

Completes the Lua migration started in #1478.

• Exposes usingLua on the Hypr singleton (bound to Hyprland.usingLua) and passes it into HyprExtras via QML binding, avoiding duplication of Quickshell's config detection logic in C++
• Gates idle/return actions in IdleMonitors.qml based on config type
• Gates applyOptions in HyprExtras to use eval hl.config instead of keyword when on Lua
• Reverts hardcoded Lua defaults in generalconfig.hpp in favor of runtime detection
• Fixes undefined workspace dispatch in Workspaces.qml

Closes #1478

[soramanew]

Overall looks pretty good, just needs a few tweaks.

[Mestane]

OMG ! I hate sed command. I'll never use it again.

[Mestane]

replaced C++ systeminfo detection with QML binding usingLua is now passed in from QML via HyprExtras { usingLua: Hyprland.usingLua } and exposed through the Hypr singleton as Hypr.usingLua, removing the need to duplicate Quickshell's config detection logic in C++.

[soramanew]

LGTM, thanks!