feat: cleanup + screenshot buttons in sidebar inspector toolbar

Two action buttons in the inspector toolbar:
- Cleanup (🧹): POSTs cleanup --all to server, shows spinner, chat
  notification on success, resets inspector state (element may be removed)
- Screenshot (📸): POSTs screenshot to server, shows spinner, chat
  notification with saved file path

Shared infrastructure:
- .inspector-action-btn CSS with loading spinner via ::after pseudo-element
- chat-notification type in addChatEntry() for system messages
- package.json version bump to 0.13.9.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

extension/sidepanel.js

@@ -135,6 +135,16 @@ function addChatEntry(entry) {
     return;
   }
 
+  // System notifications (cleanup, screenshot, errors)
+  if (entry.type === 'notification') {
+    const note = document.createElement('div');
+    note.className = 'chat-notification';
+    note.textContent = entry.message;
+    chatMessages.appendChild(note);
+    note.scrollIntoView({ behavior: 'smooth', block: 'end' });
+    return;
+  }
+
   // Agent streaming events
   if (entry.role === 'agent') {
     handleAgentEvent(entry);
@@ -1139,6 +1149,74 @@ inspectorSendBtn.addEventListener('click', () => {
   chrome.runtime.sendMessage({ type: 'sidebar-command', message });
 });
 
+// ─── Cleanup Button ─────────────────────────────────────────────
+
+const inspectorCleanupBtn = document.getElementById('inspector-cleanup-btn');
+if (inspectorCleanupBtn) {
+  inspectorCleanupBtn.addEventListener('click', async () => {
+    if (inspectorCleanupBtn.classList.contains('loading')) return;
+    if (!serverUrl || !serverToken) {
+      addChatEntry({ type: 'notification', message: 'Not connected to browse server' });
+      return;
+    }
+    inspectorCleanupBtn.classList.add('loading');
+    try {
+      const resp = await fetch(`${serverUrl}/command`, {
+        method: 'POST',
+        headers: { ...authHeaders(), 'Content-Type': 'application/json' },
+        body: JSON.stringify({ command: 'cleanup', args: ['--all'] }),
+        signal: AbortSignal.timeout(15000),
+      });
+      const text = await resp.text();
+      if (resp.ok) {
+        addChatEntry({ type: 'notification', message: text || 'Page cleaned up' });
+        // Reset inspector — selected element may have been removed
+        inspectorShowEmpty();
+      } else {
+        const err = JSON.parse(text).error || 'Cleanup failed';
+        addChatEntry({ type: 'notification', message: 'Error: ' + err });
+      }
+    } catch (err) {
+      addChatEntry({ type: 'notification', message: 'Cleanup failed: ' + err.message });
+    } finally {
+      inspectorCleanupBtn.classList.remove('loading');
+    }
+  });
+}
+
+// ─── Screenshot Button ──────────────────────────────────────────
+
+const inspectorScreenshotBtn = document.getElementById('inspector-screenshot-btn');
+if (inspectorScreenshotBtn) {
+  inspectorScreenshotBtn.addEventListener('click', async () => {
+    if (inspectorScreenshotBtn.classList.contains('loading')) return;
+    if (!serverUrl || !serverToken) {
+      addChatEntry({ type: 'notification', message: 'Not connected to browse server' });
+      return;
+    }
+    inspectorScreenshotBtn.classList.add('loading');
+    try {
+      const resp = await fetch(`${serverUrl}/command`, {
+        method: 'POST',
+        headers: { ...authHeaders(), 'Content-Type': 'application/json' },
+        body: JSON.stringify({ command: 'screenshot', args: [] }),
+        signal: AbortSignal.timeout(15000),
+      });
+      const text = await resp.text();
+      if (resp.ok) {
+        addChatEntry({ type: 'notification', message: text || 'Screenshot saved' });
+      } else {
+        const err = JSON.parse(text).error || 'Screenshot failed';
+        addChatEntry({ type: 'notification', message: 'Error: ' + err });
+      }
+    } catch (err) {
+      addChatEntry({ type: 'notification', message: 'Screenshot failed: ' + err.message });
+    } finally {
+      inspectorScreenshotBtn.classList.remove('loading');
+    }
+  });
+}
+
 // ─── Section Toggles ────────────────────────────────────────────
 
 document.querySelectorAll('.inspector-section-toggle').forEach(toggle => {