docs: add CLI documentation section with translations and code snippets; refactor mock/ to examples/, improve CLI module (bug fixes, DX, error handling)

examples/example_min_app/routers.py

@@ -0,0 +1,9 @@
+# routers.py
+from argenta import Command, Response, Router
+
+router = Router(title="Quickstart Example")
+
+@router.command(Command("hello", description="Say hello"))
+def handler(response: Response):
+    print("Hello, world!")
+