* fix(runner): surface focus-tap errors in InputText action
A failed Tap/TapSelector before InputText was swallowed, so text typed
into the wrong field (or no field) still reported success. Return the
error so the step fails explicitly.
* feat(sample-app): add username EditText and snapshot
Gives the spec a real EditText target (content-desc: username_field)
so the InputText action path can be exercised end-to-end. The typed
value is mirrored into MainActivity.username and surfaced as the
"username" snapshot for spec assertions.
* feat(sample-app): exercise InputText action against username field
Adds typeUsername action and usernameNeverShrinks property to the
sample spec, and extends the integration test to assert the bundled
spec emits an InputText(desc:username_field, "alice") action and that
the property correctly violates when a snapshot reports a shorter
string.
The old tests loaded merchant-android uiautomator dumps from /tmp and
skipped when absent. Replace with two hermetic tests that bundle
examples/sample-app/spec.ts against a synthetic hierarchy: one checks
tapClickMe fires, the other drives the three properties through a
holds/holds/violated snapshot sequence.
pj