Security: slides: Fix typst formatting

[oli-ben]

Fix the Typst formatting.

git pre-commit hook:

#!/bin/sh
# Abort the commit if any staged .typ file is not formatted per typstyle.
# Checks the staged blob (not the worktree) so unrelated edits don't interfere.

set -e

if ! command -v typstyle >/dev/null 2>&1; then
    echo "pre-commit: typstyle not found in PATH; skipping .typ format check" >&2
    exit 0
fi

# Added/Copied/Modified/Renamed, NUL-separated to handle spaces in paths.
files=$(git diff --cached --name-only --diff-filter=ACMR -z | tr '\0' '\n' | grep -E '\.typ$' || true)

[ -z "$files" ] && exit 0

bad=""
while IFS= read -r f; do
    [ -z "$f" ] && continue
    if ! git show ":$f" | typstyle --check >/dev/null 2>&1; then
        bad="$bad $f"
    fi
done <<EOF
$files
EOF

if [ -n "$bad" ]; then
    echo "pre-commit: the following staged .typ files are not formatted:" >&2
    for f in $bad; do
        printf '  %s\n' "$f" >&2
    done
    echo >&2
    echo "To fix, run:" >&2
    echo "  typstyle -i$bad" >&2
    echo "then 'git add' the files and commit again." >&2
    exit 1
fi