docs: add AI code generation requirements and comprehensive Google-style docstrings

- Add AI code generation requirements to AGENTS.md
- Add module-level docstrings to all 46 Python modules
- Add detailed Google-style docstrings to all classes and functions
- Remove all inline comments following self-documenting code principle
- Include Args, Returns, Raises sections in function docstrings
- Add Attributes and Examples sections to class docstrings

app/domain/repositories/base.py

@@ -1,4 +1,8 @@
-"""Base repository interface for DDD."""
+"""Base repository interface for DDD.
+
+This module defines the generic repository pattern interface that all
+repository implementations must follow. Provides standard CRUD operations.
+"""
 
 from abc import ABC, abstractmethod
 from typing import Generic, TypeVar
@@ -10,34 +14,76 @@ T = TypeVar("T", bound=BaseEntity)
 
 
 class Repository(ABC, Generic[T]):
-    """Generic repository interface."""
+    """Generic repository interface.
+
+    Defines the contract for repository implementations. All repositories
+    must provide standard CRUD operations for their entity type.
+
+    Type Parameters:
+        T: Entity type that must inherit from BaseEntity.
+
+    Example:
+        >>> class PostRepository(Repository[Post]):
+        ...     async def get_by_id(self, entity_id: UUID) -> Post | None:
+        ...         ...
+    """
 
     @abstractmethod
     async def get_by_id(self, entity_id: UUID) -> T | None:
-        """Get entity by ID."""
+        """Get entity by ID.
+
+        Args:
+            entity_id: Unique identifier of the entity.
+
+        Returns:
+            Entity instance if found, None otherwise.
+        """
         ...
 
     @abstractmethod
     async def get_all(self) -> list[T]:
-        """Get all entities."""
+        """Get all entities.
+
+        Returns:
+            List of all entity instances.
+        """
         ...
 
     @abstractmethod
     async def add(self, entity: T) -> None:
-        """Add new entity."""
+        """Add new entity.
+
+        Args:
+            entity: Entity instance to add.
+        """
         ...
 
     @abstractmethod
     async def update(self, entity: T) -> None:
-        """Update existing entity."""
+        """Update existing entity.
+
+        Args:
+            entity: Entity instance with updated data.
+        """
         ...
 
     @abstractmethod
     async def delete(self, entity_id: UUID) -> None:
-        """Delete entity by ID."""
+        """Delete entity by ID.
+
+        Args:
+            entity_id: Unique identifier of the entity to delete.
+        """
         ...
 
     @abstractmethod
     async def exists(self, entity_id: UUID) -> bool:
-        """Check if entity exists."""
+        """Check if entity exists.
+
+        Args:
+            entity_id: Unique identifier of the entity.
+
+        Returns:
+            True if entity exists, False otherwise.
+        """
         ...