Add integration tests covering all acceptance criteria: - Unique link generated for each exchange - Link is copyable to clipboard - Link is displayed when exchange is in appropriate state - Link leads to registration page for that specific exchange - Link uses slug instead of numeric ID for security - Link contains full URL for easy sharing Story: 2.6 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>