feat: agent overlay, stop-goal support, and state persistence across app kill

- Add draggable agent overlay pill (status dot + step text + stop button)
  that shows over other apps while connected. Fix ComposeView rendering
  in service context by providing a SavedStateRegistryOwner.
- Add stop_goal protocol message so the overlay/client can abort a
  running agent session; server aborts via AbortController.
- Persist screen-capture consent to SharedPreferences so it survives
  process death; restore on ConnectionService connect and Settings resume.
- Query AccessibilityManager for real service state instead of relying
  on in-process MutableStateFlow that resets on restart.
- Add overlay permission checklist item and SYSTEM_ALERT_WINDOW manifest
  entry.
- Filter DroidClaw's own overlay nodes from the accessibility tree so the
  agent never interacts with them.

server/src/ws/device.ts

@@ -22,7 +22,7 @@ async function hashApiKey(key: string): Promise<string> {
 }
 
 /** Track running agent sessions to prevent duplicates per device */
-const activeSessions = new Map<string, string>();
+const activeSessions = new Map<string, { goal: string; abort: AbortController }>();
 
 /**
  * Send a JSON message to a device WebSocket (safe — catches send errors).
@@ -252,7 +252,8 @@ export async function handleDeviceMessage(
       }
 
       console.log(`[Pipeline] Starting goal for device ${deviceId}: ${goal}`);
-      activeSessions.set(deviceId, goal);
+      const abortController = new AbortController();
+      activeSessions.set(deviceId, { goal, abort: abortController });
 
       sendToDevice(ws, { type: "goal_started", sessionId: deviceId, goal });
 
@@ -262,6 +263,7 @@ export async function handleDeviceMessage(
         userId,
         goal,
         llmConfig: userLlmConfig,
+        signal: abortController.signal,
         onStep(step) {
           sendToDevice(ws, {
             type: "step",
@@ -294,6 +296,23 @@ export async function handleDeviceMessage(
       break;
     }
 
+    case "stop_goal": {
+      const deviceId = ws.data.deviceId!;
+      const active = activeSessions.get(deviceId);
+      if (active) {
+        console.log(`[Pipeline] Stop requested for device ${deviceId}`);
+        active.abort.abort();
+        activeSessions.delete(deviceId);
+        sendToDevice(ws, {
+          type: "goal_completed",
+          sessionId: deviceId,
+          success: false,
+          stepsUsed: 0,
+        });
+      }
+      break;
+    }
+
     case "apps": {
       const persistentDeviceId = ws.data.persistentDeviceId;
       if (persistentDeviceId) {
@@ -360,7 +379,11 @@ export function handleDeviceClose(
   const { deviceId, userId, persistentDeviceId } = ws.data;
   if (!deviceId) return;
 
-  activeSessions.delete(deviceId);
+  const active = activeSessions.get(deviceId);
+  if (active) {
+    active.abort.abort();
+    activeSessions.delete(deviceId);
+  }
   sessions.removeDevice(deviceId);
 
   // Update device status in DB