feat: implement user authentication module

- Backend (FastAPI):
  - External API authentication (pj-auth-api.vercel.app)
  - JWT token validation with Redis session storage
  - RBAC with department isolation
  - User, Role, Department models with pjctrl_ prefix
  - Alembic migrations with project-specific version table
  - Complete test coverage (13 tests)

- Frontend (React + Vite):
  - AuthContext for state management
  - Login page with error handling
  - Protected route component
  - Dashboard with user info display

- OpenSpec:
  - 7 capability specs defined
  - add-user-auth change archived

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

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

backend/app/schemas/user.py

@@ -0,0 +1,41 @@
+from pydantic import BaseModel
+from typing import Optional, List
+from datetime import datetime
+from decimal import Decimal
+
+
+class UserBase(BaseModel):
+    email: str
+    name: str
+    department_id: Optional[str] = None
+    role_id: Optional[str] = None
+    skills: Optional[List[str]] = None
+    capacity: Optional[Decimal] = Decimal("40.00")
+
+
+class UserCreate(UserBase):
+    pass
+
+
+class UserUpdate(BaseModel):
+    name: Optional[str] = None
+    department_id: Optional[str] = None
+    role_id: Optional[str] = None
+    skills: Optional[List[str]] = None
+    capacity: Optional[Decimal] = None
+    is_active: Optional[bool] = None
+
+
+class UserResponse(UserBase):
+    id: str
+    is_active: bool
+    is_system_admin: bool
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class UserInDB(UserResponse):
+    pass