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/repositories/base.py

@@ -0,0 +1,65 @@
+"""Base repository class"""
+from typing import Generic, Type, TypeVar, Optional, List
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select, update, delete
+from sqlalchemy.orm import selectinload
+
+from app.db.base import Base
+
+ModelType = TypeVar("ModelType", bound=Base)
+
+
+class BaseRepository(Generic[ModelType]):
+    """Base repository with common CRUD operations"""
+    
+    def __init__(self, model: Type[ModelType], session: AsyncSession):
+        self.model = model
+        self.session = session
+    
+    async def create(self, **kwargs) -> ModelType:
+        """Create a new record"""
+        instance = self.model(**kwargs)
+        self.session.add(instance)
+        await self.session.flush()
+        return instance
+    
+    async def get(self, id: int) -> Optional[ModelType]:
+        """Get a record by ID"""
+        result = await self.session.execute(
+            select(self.model).where(self.model.id == id)
+        )
+        return result.scalar_one_or_none()
+    
+    async def get_multi(
+        self, 
+        skip: int = 0, 
+        limit: int = 100,
+        **filters
+    ) -> List[ModelType]:
+        """Get multiple records with pagination"""
+        query = select(self.model)
+        
+        # Apply filters
+        for key, value in filters.items():
+            if hasattr(self.model, key):
+                query = query.where(getattr(self.model, key) == value)
+        
+        query = query.offset(skip).limit(limit)
+        result = await self.session.execute(query)
+        return result.scalars().all()
+    
+    async def update(self, id: int, **kwargs) -> Optional[ModelType]:
+        """Update a record"""
+        await self.session.execute(
+            update(self.model)
+            .where(self.model.id == id)
+            .values(**kwargs)
+        )
+        return await self.get(id)
+    
+    async def delete(self, id: int) -> bool:
+        """Delete a record"""
+        result = await self.session.execute(
+            delete(self.model).where(self.model.id == id)
+        )
+        return result.rowcount > 0