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/presentation/api/v1/__init__.py

@@ -1,4 +1,8 @@
-"""API v1 router."""
+"""API v1 router.
+
+This module sets up the version 1 API router and includes
+all v1 endpoint routers.
+"""
 
 from fastapi import APIRouter