Issues fixed:
1. Frontend port is 3000 (not 5173)
2. Projects API returns 500 due to missing user
3. Foreign key constraint violation on projects_user_id_fkey
Solutions:
- Created create-mock-user.ts script
- Added user-mock-001 to database
- Created startup guide (娴嬭瘯鍜屽惎鍔?md)
- Created one-click launcher (涓€閿惎鍔?bat)
- Created diagnostic tool (璇婃柇闂.bat)
New files:
- backend/src/scripts/create-mock-user.ts
- 娴嬭瘯鍜屽惎鍔?md
- 涓€閿惎鍔?bat
- 璇婃柇闂.bat