Copilot review: the unit test covered the panel's rendering, but nothing
executed `mrtr_empty`, so the handler, its preset-registry branch, and the
showcase config entry could regress with CI green.
Adds a live modern-era test that loads `mrtr-showcase-http.json` through
`loadConfig`/`resolveConfig` — the same artifacts the README's manual
reproduction uses, so the config entry and the registry branch are covered
rather than just the fixture factory — answers the embedded elicitation, and
asserts the terminal result really is an empty `CallToolResult`: that is the
input the Tools panel must render as "completed, returned nothing".
Signed-off-by: cliffhall <cliff@futurescale.com>
f5757c0f95