feat: add create-gitlab-project.sh for Free tier

[h13]

Summary

Add scripts/create-gitlab-project.sh — a script that creates a new GitLab repository from this template without requiring Premium tier.

GitLab Free tier does not support Group project templates ("Create from template"). This script provides an equivalent workflow using the glab CLI.

What it does

1. Creates a new GitLab project via glab api
2. Copies template files (excluding template-repo-only files like docs/, README, publish.yml)
3. Generates a minimal README for the new project
4. Pushes the initial commit

Usage

# From the template repo root
./scripts/create-gitlab-project.sh --group my-org --name slack-notifier

# Then initialize GAS projects
cd ../slack-notifier
pnpm install
./scripts/init.sh --title "Slack Notifier"

Documentation

• Updated docs/setup-gitlab.md with a "Per Project (Free Tier)" section
• Updated docs/setup-gitlab.ja.md with Japanese translation
• Added notes in existing Premium-tier instructions pointing to the Free tier alternative

Design decisions

• Separate from init.sh: Repo creation and GAS project setup are different responsibilities. Keeping them separate allows re-running either independently.
• Not synced to downstream: This script is not in .templatesyncignore, so it only exists in the template repo itself.
• Minimal README: New projects get a stub README rather than the template's full README.