fix: Resolve linting issues in MCP integration

- Replace deprecated typing.Dict/List with built-in dict/list
- Fix boolean comparisons (== True/False) to direct checks
- Remove unused variables in demo script
- Update type annotations to use modern Python syntax

All pre-commit hooks should now pass.

apps/twitter_rag.py

@@ -12,7 +12,6 @@ Usage:
 import argparse
 import asyncio
 from pathlib import Path
-from typing import List
 
 from apps.base_rag_example import BaseRAGExample
 from apps.twitter_data.twitter_mcp_reader import TwitterMCPReader
@@ -113,7 +112,7 @@ class TwitterMCPRAG(BaseRAGExample):
             print("5. Try running the MCP server command directly to test it")
             return False
             
-    async def load_data(self, args) -> List[str]:
+    async def load_data(self, args) -> list[str]:
         """Load Twitter bookmarks via MCP server."""
         print(f"Connecting to Twitter MCP server: {args.mcp_server}")