fix(waa-live): gate app readiness and classify infra setup failures (#107)

* fix(waa-live): gate app readiness and classify infra setup failures

* chore(waa-live): add focus diagnostics on setup-readiness failure

* fix(waa-live): refresh remediation diagnostics and remove dead log

* test(waa-live): update focus tests for accessibility foreground checks

Author: abrichr