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/main.py

@@ -1,4 +1,8 @@
-"""Application entry point with DDD architecture."""
+"""Application entry point with DDD architecture.
+
+This module is the main entry point for the FastAPI application.
+Configures DI container, middleware, and routes following DDD principles.
+"""
 
 from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
@@ -22,16 +26,29 @@ from app.presentation import router
 
 @asynccontextmanager
 async def lifespan(app: FastAPI) -> AsyncGenerator[None]:
-    """Application lifespan manager."""
-    # Startup
+    """Application lifespan manager.
+
+    Handles startup and shutdown tasks for the application.
+
+    Args:
+        app: FastAPI application instance.
+
+    Yields:
+        None during application runtime.
+    """
     await init_db()
     yield
-    # Shutdown
     await close_db()
 
 
 def app_factory() -> FastAPI:
-    """Create and configure FastAPI application."""
+    """Create and configure FastAPI application.
+
+    Sets up DI container, exception handlers, middleware, and routes.
+
+    Returns:
+        Configured FastAPI application instance.
+    """
     app = FastAPI(
         title=settings.app.name,
         debug=settings.app.debug,
@@ -40,7 +57,6 @@ def app_factory() -> FastAPI:
         redoc_url="/redoc" if settings.is_dev else None,
     )
 
-    # Setup Dishka DI container
     container = make_async_container(
         DatabaseProvider(),
         RepositoryProvider(),
@@ -50,10 +66,8 @@ def app_factory() -> FastAPI:
     )
     setup_dishka(container, app)
 
-    # Register exception handlers
     register_exception_handlers(app)
 
-    # CORS middleware
     app.add_middleware(
         CORSMiddleware,
         allow_origins=["*"],
@@ -62,12 +76,15 @@ def app_factory() -> FastAPI:
         allow_headers=["*"],
     )
 
-    # Include API routes
     app.include_router(router, prefix="/api")
 
-    # Health check endpoint
     @app.get("/health", tags=["health"])
     async def health_check() -> dict[str, str]:
+        """Health check endpoint.
+
+        Returns:
+            Status information dictionary.
+        """
         return {
             "status": "ok",
             "app": settings.app.name,
@@ -78,7 +95,10 @@ def app_factory() -> FastAPI:
 
 
 def main() -> None:
-    """Run the application."""
+    """Run the application.
+
+    Starts uvicorn server with application factory.
+    """
     uvicorn.run(
         app_factory,
         factory=True,