Both review findings from round two.
The routing change sits in the funnel BOTH entry points share, but only the
legacy inbound handler was driven by a test — the modern leg, where an
elicitation arrives as an `input_required` result the MRTR driver unpacks and
retries, was covered by construction alone. Adds
`mrtr_app_choose_option` (a modern MRTR tool whose *embedded* elicitation
carries `_meta.ui.resourceUri`) and drives it live over a real transport: the
app answers, the retry carries that answer through `inputResponses`, and the
server echoes it back as the tool's result. A second case cancels the tool
call while the app is up and asserts the request-scoped signal aborts; a third
runs the same tool against a modern server that never advertised the
capability and asserts the native queue takes it.
The cancellation case turned up a real gap: `tryAppElicitation` mounted an app
for an already-aborted signal (the caller cancelled during an earlier MRTR
round), leaving a modal nobody was waiting on and a promise that could never
settle. It now throws the abort straight through.
Also fixes the smoke count in the root README, which still said "two"
headless-Chromium smokes and then introduced a third.
Signed-off-by: cliffhall <cliff@futurescale.com>
44010c313b