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

docs/code_snippets/cli/app_instance.py

@@ -0,0 +1,16 @@
+from argenta import App, Orchestrator
+from argenta.command import Router, Command, Response
+
+router = Router(title="Example")
+
+@router.command(Command("hello", description="Say hello"))
+def hello_handler(response: Response):
+    print("Hello, world!")
+
+app = App()
+app.include_router(router)
+
+orchestrator = Orchestrator()
+
+if __name__ == "__main__":
+    orchestrator.run_repl(app)