feat: initial dashboard implementation and robust attendance parsing

- Added a Makefile to easily run project scripts (fees, match, web, image)
- Modified attendance.py to dynamically handle a variable number of header rows from the Google Sheet
- Updated both attendance calculations and calculate_fees terminal output to show actual attendance counts (e.g., '750 CZK (3)')
- Created a Flask web dashboard (app.py and templates/fees.html) to view member fees in an attractive, condensed, terminal-like UI
- Bound the Flask server to port 5000 and added a routing alias from '/' to '/fees'
- Configured Python virtual environment (.venv) creation directly into the Makefile to resolve global pip install errors on macOS

Co-authored-by: Antigravity <antigravity@deepmind.com>

build/entrypoint.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+set -euo pipefail
+
+echo "[entrypoint] Starting Flask app on port 5001..."
+
+# Running the app directly via python
+# For a production setup, we would ideally use gunicorn/waitress, but sticking to what's in app.py for now.
+exec python3 /app/app.py