fix: add __init__.py to all packages, create venv setup

- Added __init__.py to scrapers, processing, graph, ai, api,
blockchain, config, tests folders
- Fixes ModuleNotFoundError when running scrapers
- Added main.py as project entry point
- Updated .gitignore to exclude venv/ and __pycache__/
- All scripts must now run from project root with: python -m scrapers.X

main.py

@@ -0,0 +1,16 @@
+"""
+BharatGraph - Main entry point
+Run scrapers from project root to avoid import issues.
+Usage: python main.py
+"""
+
+import sys
+import os
+
+# This ensures all imports work from project root
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+
+if __name__ == "__main__":
+    print("BharatGraph is ready.")
+    print("Run scrapers like: python -m scrapers.datagov_scraper")
+