fix(host-agent): distinguish connected devices from busy-with-task in console

DeviceManager marks a device "busy" as soon as an Appium/WDA session is
connected, which is unrelated to whether a task is currently executing on
it. The Host Agent's local console displayed this raw status, making
connected-but-idle devices look permanently busy. Cross-reference the
device id against AgentStatusTracker's current_assignment (already
tracked via mark_assignment_started/finished) to show "connected" unless
a task is actually running on that device.

apps/device-host-agent/host_agent/web/app.py

@@ -108,6 +108,17 @@ def _login_page(
     return HTMLResponse(_chrome("Login", body, session=None))
 
 
+def _device_display_status(device: Any, *, busy_device_id: str | None) -> str:
+    """Connected-but-idle devices report "busy" at the DeviceManager layer
+    (an active Appium/WDA session is required to reuse it), which is not the
+    same as a task currently running on that device. Only the device actually
+    bound to the current assignment should read as "busy" here.
+    """
+    if device.status == "busy" and device.id != busy_device_id:
+        return "connected"
+    return device.status
+
+
 def _dashboard_body(
     *,
     identity: HostIdentityState | None,
@@ -118,6 +129,7 @@ def _dashboard_body(
     heartbeat = snapshot.get("last_heartbeat")
     assignment = snapshot.get("current_assignment")
     policy = snapshot.get("host_policy")
+    busy_device_id = assignment["device_id"] if assignment else None
     heartbeat_text = (
         f"{'ok' if heartbeat['ok'] else 'failed'} at {heartbeat['at']} "
         f"({heartbeat['device_count']} devices)"
@@ -143,7 +155,8 @@ def _dashboard_body(
     )
     device_rows = "".join(
         f"<tr><td>{escape(device.id)}</td><td>{escape(device.name or '')}</td>"
-        f"<td>{escape(device.driver_type)}</td><td>{escape(device.status)}</td></tr>"
+        f"<td>{escape(device.driver_type)}</td>"
+        f"<td>{escape(_device_display_status(device, busy_device_id=busy_device_id))}</td></tr>"
         for device in devices
     )
     return f"""
@@ -403,12 +416,14 @@ def create_console_app(
         session: SessionState = Depends(require_session),
     ) -> JSONResponse:
         snapshot = status_tracker.snapshot()
+        current_assignment = snapshot.get("current_assignment")
+        busy_device_id = current_assignment["device_id"] if current_assignment else None
         devices = [
             {
                 "id": device.id,
                 "name": device.name,
                 "driver_type": device.driver_type,
-                "status": device.status,
+                "status": _device_display_status(device, busy_device_id=busy_device_id),
             }
             for device in manager.list_devices()
         ]