Initial commit: database schema, data source docs, chapter variable references

.gitignore

@@ -0,0 +1,42 @@
+# Large source data files — not tracked
+data/raw/
+*.shp
+*.dbf
+*.shx
+*.prj
+*.sbn
+*.sbx
+*.sbx
+*.cpg
+*.shp.xml
+*.shp.ea.iso.xml
+*.shp.iso.xml
+
+# CSV data files (large)
+*.csv
+
+# Jupyter
+.ipynb_checkpoints/
+**/.ipynb_checkpoints/
+
+# Python
+__pycache__/
+*.py[cod]
+*.egg-info/
+.env
+.venv/
+venv/
+
+# Figures (generated outputs — commit selectively)
+figures/**/*.png
+figures/**/*.pdf
+figures/**/*.svg
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Editor
+.vscode/
+*.swp
+*~