fix: add updatedActivityId watcher to ActivityMonitor component

- Add updatedActivityId method to watch for changes to activityId property
- When activityId is set/updated, automatically hydrate the activity and enable polling
- This allows the activity monitor to display content when activityId is bound from parent component
- Fixes issue where activity monitor was empty because activity wasn't loaded

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Livewire/ActivityMonitor.php

@@ -44,6 +44,14 @@ class ActivityMonitor extends Component
         $this->activity = Activity::find($this->activityId);
     }
 
+    public function updatedActivityId($value)
+    {
+        if ($value) {
+            $this->hydrateActivity();
+            $this->isPollingActive = true;
+        }
+    }
+
     public function polling()
     {
         $this->hydrateActivity();