feat: OAuth 2.0 백엔드 시스템 구현 완료

Phase 1 & 2 완료:
- 프로젝트 기본 구조 설정
- Docker Compose 환경 구성 (MongoDB, Redis, Backend, Frontend)
- FastAPI 기반 OAuth 2.0 백엔드 구현

주요 기능:
- JWT 기반 인증 시스템
- 3단계 권한 체계 (System Admin/Group Admin/User)
- 사용자 관리 CRUD API
- 애플리케이션 관리 CRUD API
- OAuth 2.0 Authorization Code Flow
- Refresh Token 관리
- 인증 히스토리 추적

API 엔드포인트:
- /auth/* - 인증 관련 (register, login, logout, refresh)
- /users/* - 사용자 관리
- /applications/* - 애플리케이션 관리
- /oauth/* - OAuth 2.0 플로우

보안 기능:
- bcrypt 비밀번호 해싱
- JWT 토큰 인증
- CORS 설정
- Rate limiting 준비

🤖 Generated with Claude Code

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

oauth/backend/app/models/application.py

@@ -0,0 +1,79 @@
+"""Application model definitions"""
+
+from typing import List, Optional, Dict, Any
+from pydantic import BaseModel, Field, ConfigDict
+from datetime import datetime
+from bson import ObjectId
+
+
+class ApplicationTheme(BaseModel):
+    """Application theme configuration"""
+    primary_color: str = "#1976d2"
+    secondary_color: str = "#dc004e"
+    logo_url: Optional[str] = None
+    favicon_url: Optional[str] = None
+    font_family: str = "Roboto, sans-serif"
+    custom_css: Optional[str] = None
+
+
+class ApplicationBase(BaseModel):
+    """Base application model"""
+    app_name: str = Field(..., min_length=3, max_length=100)
+    description: Optional[str] = None
+    redirect_uris: List[str] = []
+    allowed_origins: List[str] = []
+    theme: Optional[ApplicationTheme] = ApplicationTheme()
+    permissions: List[str] = ["sso", "name", "email"]  # Default permissions
+    is_active: bool = True
+
+
+class ApplicationCreate(ApplicationBase):
+    """Application creation model"""
+    pass
+
+
+class ApplicationUpdate(BaseModel):
+    """Application update model"""
+    app_name: Optional[str] = Field(None, min_length=3, max_length=100)
+    description: Optional[str] = None
+    redirect_uris: Optional[List[str]] = None
+    allowed_origins: Optional[List[str]] = None
+    theme: Optional[ApplicationTheme] = None
+    permissions: Optional[List[str]] = None
+    is_active: Optional[bool] = None
+
+
+class Application(ApplicationBase):
+    """Application response model"""
+    id: str = Field(alias="_id")
+    client_id: str
+    client_secret: str
+    created_by: str
+    created_at: datetime
+    updated_at: datetime
+    
+    model_config = ConfigDict(
+        populate_by_name=True,
+        arbitrary_types_allowed=True,
+        json_encoders={ObjectId: str}
+    )
+
+
+class ApplicationInDB(Application):
+    """Application model in database"""
+    pass
+
+
+class ApplicationPublic(BaseModel):
+    """Public application information (no secret)"""
+    id: str = Field(alias="_id")
+    app_name: str
+    description: Optional[str] = None
+    theme: Optional[ApplicationTheme] = None
+    permissions: List[str] = []
+    
+    model_config = ConfigDict(
+        populate_by_name=True,
+        arbitrary_types_allowed=True,
+        json_encoders={ObjectId: str}
+    )