Switch to debian:bookworm-slim, drop enumitem and texlive-latex-extra

- Replace texlive/texlive:latest with debian:bookworm-slim + targeted
  TeX Live packages (texlive-latex-recommended, texlive-pictures,
  texlive-fonts-recommended)
- Remove \usepackage{enumitem} from brevetkarte.tex and template;
  replace list options with plain LaTeX \setlength equivalents
- Add Export Brevetkarte.csv to .gitignore (real participant data)
- Add Export Brevetkarte.csv.example with anonymised sample data

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

Dockerfile

@@ -1,7 +1,9 @@
-FROM texlive/texlive:latest
+FROM debian:bookworm-slim
 
-# Install additional packages if needed
-RUN apt-get update && apt-get install -y \
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    texlive-latex-recommended \
+    texlive-pictures \
+    texlive-fonts-recommended \
     make \
     && rm -rf /var/lib/apt/lists/*