chore: import upstream snapshot with attribution

showcase/integrations/claude-sdk-python/qa/prebuilt-sidebar.md

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+# QA: Pre-Built Sidebar — Claude Agent SDK (Python)
+
+## Prerequisites
+
+- Demo is deployed and accessible
+- Agent backend is healthy (check /api/health)
+
+## Test Steps
+
+### 1. Basic Functionality
+
+- [ ] Navigate to `/demos/prebuilt-sidebar`
+- [ ] Verify the main content heading "Sidebar demo — click the launcher" is visible
+- [ ] Verify `<CopilotSidebar />` opens by default (sidebar is visible)
+- [ ] Verify the sidebar has a chat input
+- [ ] Send a basic message (e.g. "Say hi")
+- [ ] Verify the agent responds in the sidebar
+
+### 2. Feature-Specific Checks
+
+#### Suggestions
+
+- [ ] Verify the "Say hi" suggestion button is visible inside the sidebar
+- [ ] Click the suggestion and verify it sends the message
+
+#### Sidebar Toggle
+
+- [ ] Close the sidebar via its toggle/launcher
+- [ ] Reopen the sidebar and verify the conversation is preserved
+
+### 3. Error Handling
+
+- [ ] Verify no console errors during normal usage
+- [ ] Verify closing/opening the sidebar does not break the chat state
+
+## Expected Results
+
+- Page loads within 3 seconds
+- Sidebar renders with launcher
+- Agent responds within 10 seconds