Add CSV-based personalized card generation

Add template-based system for generating personalized brevet cards
from CSV data. Uses proper separation of concerns with template file
and Python script.

- Add brevetkarte-template.tex with placeholders
- Add generate_cards.py to read CSV and populate template
- Update Makefile with generate-personalized and build-personalized targets
- Update .gitignore to exclude generated files

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.gitignore

@@ -10,6 +10,9 @@
 # Rendered PDFs
 *.pdf
 
+# Generated files
+brevetkarte-personalized.tex
+
 # macOS
 .DS_Store