feat: Implement backend core functionality for news-engine-console

Phase 1 Backend Implementation:
- ✅ MongoDB data models (Keyword, Pipeline, User, Application)
- ✅ Pydantic schemas for all models with validation
- ✅ KeywordService: Full CRUD, filtering, pagination, stats, toggle status
- ✅ PipelineService: Full CRUD, start/stop/restart, logs, config management
- ✅ Keywords API: 8 endpoints with complete functionality
- ✅ Pipelines API: 11 endpoints with complete functionality
- ✅ Updated TODO.md to reflect completion

Key Features:
- Async MongoDB operations with Motor
- Comprehensive filtering and pagination support
- Pipeline logging system
- Statistics tracking for keywords and pipelines
- Proper error handling with HTTP status codes
- Type-safe request/response models

Files Added:
- models/: 4 data models with PyObjectId support
- schemas/: 4 schema modules with Create/Update/Response patterns
- services/: KeywordService (234 lines) + PipelineService (332 lines)

Files Modified:
- api/keywords.py: 40 → 212 lines (complete implementation)
- api/pipelines.py: 25 → 300 lines (complete implementation)
- TODO.md: Updated checklist with completed items

Next Steps:
- UserService with authentication
- ApplicationService for OAuth2
- MonitoringService
- Redis integration
- Frontend implementation

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

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

services/news-engine-console/backend/app/schemas/user.py

@@ -0,0 +1,55 @@
+from datetime import datetime
+from typing import Optional
+from pydantic import BaseModel, Field, EmailStr
+
+
+class UserBase(BaseModel):
+    """Base user schema"""
+    username: str = Field(..., min_length=3, max_length=50)
+    email: EmailStr
+    full_name: str = Field(..., min_length=1, max_length=100)
+    role: str = Field(default="viewer", description="Role: admin, editor, viewer")
+
+
+class UserCreate(UserBase):
+    """Schema for creating a new user"""
+    password: str = Field(..., min_length=8, max_length=100)
+
+
+class UserUpdate(BaseModel):
+    """Schema for updating a user (all fields optional)"""
+    email: Optional[EmailStr] = None
+    full_name: Optional[str] = Field(None, min_length=1, max_length=100)
+    role: Optional[str] = None
+    disabled: Optional[bool] = None
+    password: Optional[str] = Field(None, min_length=8, max_length=100)
+
+
+class UserResponse(UserBase):
+    """Schema for user response (without password)"""
+    id: str = Field(..., alias="_id")
+    disabled: bool
+    created_at: datetime
+    last_login: Optional[datetime] = None
+
+    class Config:
+        populate_by_name = True
+        from_attributes = True
+
+
+class UserLogin(BaseModel):
+    """Schema for user login"""
+    username: str
+    password: str
+
+
+class Token(BaseModel):
+    """Schema for JWT token response"""
+    access_token: str
+    token_type: str = "bearer"
+    expires_in: int
+
+
+class TokenData(BaseModel):
+    """Schema for decoded token data"""
+    username: Optional[str] = None