feat: add defeatbeta-api integration with comprehensive comparison tools

- Add defeatbeta-api as primary financial data source (replaces yfinance for analysis)
- Add comprehensive Jupyter notebook tutorial (defeatbeta_tutorial.ipynb)
- Add API comparison script (compare_apis.py)
- Add data exploration script (explore_data.py)
- Add basic test script (test_defeatbeta.py)
- Add notebook runner script (run_notebook.sh)
- Add org-mode mapping documentation (docs/defeatbeta_mapping.org)
- Update pyproject.toml with defeatbeta-api dependency
- Add defeatbeta-api as git submodule for reference

DefeatBeta Advantages:
- No rate limits (HuggingFace hosted)
- Historical financial ratios (ROE, ROIC, WACC time series)
- Earnings call transcripts access
- Revenue segmentation by product/geography
- Automated DCF valuation with Excel output
- DuckDB-powered fast queries

Note: .envrc, .jupyter_checkpoints/, __marimo__/, AAPL.xlsx, tearsheet.html
and other generated files intentionally excluded

run_notebook.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+# Run the DefeatBeta tutorial notebook with proper environment
+
+echo "📚 DefeatBeta-API Tutorial Notebook"
+echo "===================================="
+echo ""
+echo "This script will open the tutorial notebook with proper uv environment."
+echo ""
+
+# Check if jupyter is available
+if ! command -v jupyter &> /dev/null; then
+    echo "❌ Jupyter not found. Installing..."
+    uv add jupyter
+fi
+
+# Check if the notebook exists
+if [ ! -f "defeatbeta_tutorial.ipynb" ]; then
+    echo "❌ Notebook not found: defeatbeta_tutorial.ipynb"
+    exit 1
+fi
+
+echo "✅ Environment ready"
+echo ""
+echo "Starting Jupyter notebook..."
+echo ""
+echo "📝 Contents:"
+echo "   1. Quick Performance Test"
+echo "   2. Price Data Comparison"
+echo "   3. Valuation Metrics"
+echo "   4. Financial Statements"
+echo "   5. Financial Ratios"
+echo "   6. Growth & Margin Metrics"
+echo "   7. Earnings Transcripts (Unique!)"
+echo "   8. Revenue Breakdown (Unique!)"
+echo "   9. DCF Valuation (Unique!)"
+echo "   10. Interactive Stock Analysis"
+echo "   11. Stock Comparison"
+echo "   12. Complete Method Reference"
+echo ""
+echo "🚀 Launching notebook..."
+echo ""
+
+# Run jupyter with uv
+cd /home/df/scratch/trading/learn-trading
+uv run jupyter notebook defeatbeta_tutorial.ipynb