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

static/css/main.css

@@ -500,6 +500,7 @@
     border-radius: var(--radius-sm);
     cursor: move;
     display: flex;
+    flex-direction: column;
     align-items: center;
     justify-content: center;
     font-size: 12px;
@@ -507,7 +508,16 @@
     background: var(--accent-container);
     min-width: 80px;
     min-height: 50px;
+    user-select: none;
+    overflow: hidden;
 }
+.ep-icon { font-size: 24px; }
+.ep-name { font-size: 11px; color: var(--text-secondary); margin-top: 4px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 90%; }
+.ep-actions { position: absolute; top: 2px; right: 2px; }
+
+.editor-dash-item:active { opacity: 0.7; }
+
+.forward-toggle input { margin-right: 4px; }
 
 /* ===== Debug Page ===== */
 .debug-container {