feat: 1,4,6 - scene canvas editor, systemd service, F1 composite dashboard

- Scene editor: drag-drop dashboards from sidebar to canvas, reposition, delete placements, save/load
- Systemd service: turbosu.service with frpc dependency, restart on failure
- F1 composite: speed/RPM/lap/gear/throttle/brake/fuel/DRS, 16:9, NEXT ART font

dashboards/f1_composite/manifest.json

@@ -0,0 +1,14 @@
+{
+    "id": "f1_composite",
+    "name": "F1 复合仪表盘",
+    "category": "f1",
+    "description": "F1 专属复合仪表：速度+RPM大字+档位圆环+油门刹车行程+油量+圈速",
+    "author": "Yei.J. (AskaEth)",
+    "version": "1.0.0",
+    "supported_games": "f1_24",
+    "config": {
+        "icon": "🏎️",
+        "aspect_ratio": "16:9",
+        "render_mode": "contain"
+    }
+}