Use high reasoning effort for changelog generation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: wesm

scripts/changelog.sh

@@ -34,7 +34,7 @@ echo "Using codex to generate changelog..." >&2
 TMPFILE=$(mktemp)
 trap 'rm -f "$TMPFILE"' EXIT
 
-codex exec --skip-git-repo-check -o "$TMPFILE" - >/dev/null <<EOF
+codex exec --skip-git-repo-check -c reasoning_effort=high -o "$TMPFILE" - >/dev/null <<EOF
 You are generating a changelog for roborev version $VERSION.
 
 Here are the commits since the last release: