Fix Gemini INVALID_ARGUMENT: remove empty string from notion filter_type enum

Fix lazy token loading in tools, add github_list_commits tool, load_dotenv in main

Switch tools agent to Gemini primary, OpenAI fallback

Integrate tools agent (GitHub/Slack/Notion) into main app under /tools prefix

Add toolsforgitnotionslack folder as a folder for my code which can be run nativelly and as a fastapi endpoint