Add caching tests

[MDA2AV]

• CAP-IMS-FUTURE — Sends If-Modified-Since with a year-2099 date; Pass=200, Warn=304
  • CAP-IMS-INVALID — Sends If-Modified-Since: not-a-date; Pass=200, Warn=304
  • CAP-INM-UNQUOTED — Captures ETag, strips quotes, sends unquoted in If-None-Match; Pass=200, Warn=304
  • CAP-ETAG-WEAK — Captures ETag, prepends W/ if strong, sends via If-None-Match; Pass=304, Warn=200

[sonarqubecloud]

Quality Gate failed

Failed conditions
71.1% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud