Add blanko build target, fix preamble duplication, update event config and margins

- Add --blanko flag to generate_cards.py for blank cards (no CSV needed), 2-up layout
- Fix preamble duplication bug affecting both blanko and multi-participant personalized builds
- Add make build-blanko target; default make now builds personalized + blanko
- Reduce page margins from 0.8cm to 0.4cm for Kyocera P6026
- Widen tikzpicture columns (6.9→7.2cm) and tabular columns (6.6→7.0cm) to fill page width
- Update event.yml for BRM400 Bonn–Lüttich–Bastogne–Bonn, 9. Mai 2026, with 6 controls

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

generate_cards.py

@@ -2,6 +2,7 @@
 """
 Generate personalized brevet cards from CSV and event config.
 """
+import argparse
 import csv
 import sys
 from pathlib import Path
@@ -92,7 +93,23 @@ def generate_card_from_template(template, data):
     return card
 
 
+def generate_blanko_card(template):
+    """Generate a blank card with empty participant fields."""
+    card = template.replace('{{NAME}}', '')
+    card = card.replace('{{STREET}}', '')
+    card = card.replace('{{PLZ_ORT}}', '')
+    card = card.replace('{{LAND}}', '')
+    card = card.replace('{{MEDAILLE}}', '')
+    card = card.replace('{{STARTNR}}', '')
+    return card
+
+
 def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--blanko', action='store_true',
+                        help='Generate blank card without participant data')
+    args = parser.parse_args()
+
     csv_file = Path("export_brevetcard.csv")
     template_file = Path("brevetkarte-template.tex")
     backside_template_file = Path("brevetkarte-rueckseite-template.tex")
@@ -112,6 +129,24 @@ def main():
     template = template_file.read_text(encoding='utf-8')
     template = apply_event_placeholders(template, event_config)
 
+    # Split preamble from body so \begin{document} appears only once per file
+    marker = '\\begin{document}'
+    doc_idx = template.find(marker)
+    preamble = template[:doc_idx + len(marker)]
+    body = template[doc_idx + len(marker):]
+
+    if args.blanko:
+        blanko_output_file = Path("brevetkarte-blanko.tex")
+        blanko_body = generate_blanko_card(body)
+        blanko_output = preamble + blanko_body + "\n\\vspace{0.8cm}\n\n" + blanko_body + "\n\\end{document}\n"
+        blanko_output_file.write_text(blanko_output, encoding='utf-8')
+        print(f"Generated {blanko_output_file}")
+        backside_template = backside_template_file.read_text(encoding='utf-8')
+        backside_output = generate_backside(backside_template, event_config)
+        backside_output_file.write_text(backside_output, encoding='utf-8')
+        print(f"Generated {backside_output_file}")
+        return
+
     print(f"Reading participant data from {csv_file}...")
     participants = []
     with open(csv_file, 'r', encoding='utf-8-sig') as f:
@@ -129,10 +164,10 @@ def main():
     # Generate personalized front side
     cards = []
     for participant in participants:
-        card = generate_card_from_template(template, participant)
+        card = generate_card_from_template(body, participant)
         cards.append(card)
 
-    document_parts = []
+    document_parts = [preamble]
     for i, card in enumerate(cards):
         document_parts.append(card)
         if i % 2 == 0 and i < len(cards) - 1: