Add multi-site Caddy helpers and document usage

- add startup/shutdown scripts that render a Caddyfile from JSON config and run health checks

- add Python utilities and a sample sites.json for declarative multi-site configuration

- document the workflow and ignore generated Caddy state artifacts

- normalize double-quote style across challenge workflow controllers, nodes, and tests

api/tests/test_containers_integration_tests/test_web_challenges.py

@@ -10,5 +10,3 @@ class TestWebChallenges:
         assert resp.status_code == 200
         data = resp.get_json()
         assert data["result"] == "success"
-
-

api/tests/test_containers_integration_tests/test_web_red_blue_challenges.py

@@ -9,5 +9,3 @@ class TestWebRedBlueChallenges:
         assert resp.status_code == 200
         data = resp.get_json()
         assert data["result"] == "success"
-
-