fix: Better Auth integration - map sign-in/email to backend login, exclude auth from rewrites

fix: Use direct backend /api/auth/login instead of Better Auth sign-in endpoint

fix: Use relative URLs instead of localhost for HF Space deployment

feat: Update with all 12 gap fixes - SQLModel, Better Auth, OpenAI Agents, Urdu, Voice

fix: Use relative URLs for API calls in production

feat: Deploy Todo App Phase 5 to Hugging Face Space