feat(demo): uncomment feature demos and add fake-useragent dependency

Uncomments demonstration code for memory dispatcher, streaming support,
content scraping, JSON schema generation, LLM markdown, and robots compliance
in the v0.4.3b2 features demo file. Also adds fake-useragent package as a
project dependency.

This change makes all feature demonstrations active by default and ensures
proper user agent handling capabilities.

docs/examples/v0_4_3b2_features_demo.py

@@ -333,18 +333,18 @@ async def main():
     
     # Efficiency & Speed Demos
     print("\n🚀 EFFICIENCY & SPEED DEMOS")
-    # await demo_memory_dispatcher()
-    # await demo_streaming_support()
-    # await demo_content_scraping()
+    await demo_memory_dispatcher()
+    await demo_streaming_support()
+    await demo_content_scraping()
     
     # # LLM Integration Demos
     print("\n🤖 LLM INTEGRATION DEMOS")
-    # await demo_json_schema_generation()
-    # await demo_llm_markdown()
+    await demo_json_schema_generation()
+    await demo_llm_markdown()
     
     # # Core Improvements
     print("\n🔧 CORE IMPROVEMENT DEMOS")
-    # await demo_robots_compliance()
+    await demo_robots_compliance()
     await demo_proxy_rotation()
 
 if __name__ == "__main__":