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/infrastructure/database/models.py

@@ -1,4 +1,8 @@
-"""SQLAlchemy ORM models."""
+"""SQLAlchemy ORM models.
+
+This module defines the database ORM models that map to database tables.
+Models are used by repositories for data persistence.
+"""
 
 from datetime import UTC, datetime
 from uuid import uuid4
@@ -10,7 +14,25 @@ Base = declarative_base()
 
 
 class PostORM(Base):  # type: ignore[valid-type,misc]
-    """SQLAlchemy model for Blog Post."""
+    """SQLAlchemy model for Blog Post.
+
+    Database table representation of blog posts.
+    Maps to the 'posts' table with all post attributes.
+
+    Attributes:
+        id: Primary key as UUID string.
+        title: Post title (max 200 chars).
+        content: Post content (text).
+        slug: URL-friendly unique identifier.
+        author_id: Author reference.
+        published: Publication status flag.
+        tags: JSON array of tags.
+        created_at: Creation timestamp.
+        updated_at: Last update timestamp.
+
+    Example:
+        >>> post = PostORM(title="Post", content="...", slug="post", author_id="user-1")
+    """
 
     __tablename__ = "posts"