chore: add sproutclaw git workflow and track local extensions

Document main/upstream-sync/feature branch strategy, add sync/push
scripts, track .pi/agent extensions and webui in git, and disable
startup changelog via showChangelogOnStartup.

Co-authored-by: Cursor <cursoragent@cursor.com>

.pi/agent/extensions/webui/frontend/src/routes/ChatPage.tsx

@@ -0,0 +1,13 @@
+import { ChatInput } from "../components/chat/ChatInput";
+import { MessageList } from "../components/chat/MessageList";
+import { Header } from "../components/layout/Header";
+
+export function ChatPage() {
+	return (
+		<>
+			<Header />
+			<MessageList />
+			<ChatInput />
+		</>
+	);
+}