Add blank workbook template, example rules file, and Create blank workbook button

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Dockerfile

@@ -7,6 +7,7 @@ COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
 COPY statement_loader.py app.py app_page.html app_dashboard.html ./
+COPY template/ ./template/
 
 # statements, Bills_Tracker.xlsx and backups live in this volume, never in the image
 RUN useradd -m -u 1000 app && mkdir /data && chown app /data