Rewrite as uv-based Flask web app with Dockerfile

- Flask dashboard with Plotly charts (stores, monthly, hourly, weekday, heatmap)
- Spotify Wrapped-style summary with year dropdown and inflation toggle
- CSV upload flow (ephemeral, no storage)
- Homepage with upload and saved data options
- Import script for loading CSVs into SQLite
- Dockerized with gunicorn for production

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,11 @@
+.git
+.venv
+env
+venv
+__pycache__
+*.pyc
+.DS_Store
+images
+*.db
+*.csv
+*.db.bak