Milestone 1: Complete backend feature with: - Migration with CHECK (amount > 0) constraint - Repository with mapRow() for snake_case -> camelCase - Service with CRUD and vehicle authorization - Controller with HTTP handlers - Routes registered at /api/ownership-costs - Validation with Zod schemas - README with endpoint documentation 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>