Add complete ai.card Rust implementation

- Implement complete Rust API server with axum framework
- Add database abstraction supporting PostgreSQL and SQLite
- Implement comprehensive gacha system with probability calculations
- Add JWT authentication with atproto DID integration
- Create card master data system with rarities (Normal, Rare, SuperRare, Kira, Unique)
- Implement draw history tracking and collection management
- Add API endpoints for authentication, card drawing, and collection viewing
- Include database migrations for both PostgreSQL and SQLite
- Maintain full compatibility with Python API implementation
- Add comprehensive documentation and development guide

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

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

python/api/app/models/__init__.py

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+# Models Package

python/api/app/models/card.py

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+"""Card data models"""
+from datetime import datetime
+from enum import Enum
+from typing import Optional
+from pydantic import BaseModel, Field
+
+
+class CardRarity(str, Enum):
+    """カードのレアリティ"""
+    NORMAL = "normal"
+    RARE = "rare"
+    SUPER_RARE = "super_rare"
+    KIRA = "kira"  # キラカード（0.1%）
+    UNIQUE = "unique"  # uniqueカード（0.0001%）
+
+
+class CardBase(BaseModel):
+    """カードの基本情報"""
+    id: int = Field(..., ge=0, le=15, description="カード種類ID (0-15)")
+    cp: int = Field(..., ge=1, le=999, description="カードパワー")
+    status: CardRarity = Field(default=CardRarity.NORMAL, description="レアリティ")
+    skill: Optional[str] = Field(None, description="スキル情報")
+
+
+class Card(CardBase):
+    """所有カード情報"""
+    owner_did: str = Field(..., description="所有者のatproto DID")
+    obtained_at: datetime = Field(default_factory=datetime.utcnow, description="取得日時")
+    is_unique: bool = Field(default=False, description="uniqueカードフラグ")
+    unique_id: Optional[str] = Field(None, description="unique時のグローバルID")
+    
+    class Config:
+        json_encoders = {
+            datetime: lambda v: v.isoformat()
+        }
+
+
+class CardDraw(BaseModel):
+    """カード抽選リクエスト"""
+    user_did: str = Field(..., description="ユーザーのDID")
+    is_paid: bool = Field(default=False, description="課金ガチャかどうか")
+
+
+class CardDrawResult(BaseModel):
+    """カード抽選結果"""
+    card: Card
+    is_new: bool = Field(..., description="新規取得かどうか")
+    animation_type: str = Field(..., description="演出タイプ")
+    
+    
+class UniqueCardRegistry(BaseModel):
+    """uniqueカードの登録情報"""
+    card_id: int
+    unique_id: str
+    owner_did: str
+    obtained_at: datetime
+    verse_skill_id: Optional[str] = None