feat: Extract hardcoded configs to environment variables

- Add environment variable configuration for backend and frontend
- Backend: DB_POOL_SIZE, JWT_EXPIRE_HOURS, timeout configs, directory paths
- Frontend: VITE_API_BASE_URL, VITE_UPLOAD_TIMEOUT, Whisper configs
- Create deployment script (scripts/deploy-backend.sh)
- Create 1Panel deployment guide (docs/1panel-deployment.md)
- Update DEPLOYMENT.md with env var documentation
- Create README.md with project overview
- Remove obsolete PRD.md, SDD.md, TDD.md (replaced by OpenSpec)
- Keep CORS allow_origins=["*"] for Electron EXE distribution

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/routers/auth.py

@@ -17,7 +17,7 @@ def create_token(email: str, role: str) -> str:
     payload = {
         "email": email,
         "role": role,
-        "exp": datetime.utcnow() + timedelta(hours=24),
+        "exp": datetime.utcnow() + timedelta(hours=settings.JWT_EXPIRE_HOURS),
     }
     return jwt.encode(payload, settings.JWT_SECRET, algorithm="HS256")
 
@@ -67,7 +67,7 @@ async def login(request: LoginRequest):
             response = await client.post(
                 settings.AUTH_API_URL,
                 json={"username": request.email, "password": request.password},
-                timeout=30.0,
+                timeout=settings.auth_timeout_seconds,
             )
 
             if response.status_code == 401: