refactor: rename canto-backend → backend, canto-frontend → frontend

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/requirements.txt

@@ -0,0 +1,26 @@
+fastapi==0.115.0
+uvicorn[standard]==0.32.0
+pydantic[email]==2.9.0
+pydantic-settings==2.5.2
+python-multipart==0.0.12
+python-jose[cryptography]==3.3.0
+passlib==1.7.4
+bcrypt==3.2.2
+cryptography>=41.0.0
+sqlalchemy==2.0.35
+aiosqlite==0.20.0
+soundfile==0.12.1
+scipy>=1.11.0
+torch>=2.0.0
+numpy>=1.24.0
+pydub>=0.25.0
+requests>=2.31.0
+apscheduler>=3.10.0
+slowapi==0.1.9
+locust==2.20.0
+pytest==8.3.0
+pytest-cov==4.1.0
+pytest-asyncio==0.23.0
+httpx==0.27.0
+websockets>=12.0
+EbookLib>=0.18