feat(ags-v3): desktop adaptation — ultrawide scaling, brain power panel, system stats

- Scaling 16px base pour ultrawide 3440x1440
- Bar: CPU/RAM/GPU visible, media single player (skip playerctld), network tooltip LAN/WAN IPv4
- Volume: class module pour sizing cohérent
- Battery: désactivé (PC fixe)
- Clock: tooltip calendrier + uptime
- BrainPower: panel enrichi (focus, session, intentions, todos, repos git, derniers commits)
- App: BrainPower sur moniteur principal uniquement
- Heartbeat: Layer.TOP pour compatibilité COSMIC

ags-v3/app.ts

@@ -7,11 +7,14 @@ import BrainPower from "./widget/panels/BrainPower"
 app.start({
   css: style,
   main() {
-    for (const monitor of app.get_monitors()) {
+    const monitors = app.get_monitors()
+    for (const monitor of monitors) {
       Heartbeat(monitor)
       Bar(monitor)
-      BrainPower(monitor)
     }
+    // Brain Power on primary monitor only
+    const primary = monitors[0]
+    if (primary) BrainPower(primary)
   },
   requestHandler(request: any, res: (response: any) => void) {
     const cmd = String(request)