71735354 made TvTextInputPresentation.automatic use native platform
input for single-line Apple TV fields, and 829d3745 migrated the search
and Add Jellyfin suites to it. These five cases still expected the
Flutter on-screen keyboard widget and failed looking for a panel that no
longer exists.
Drives the native path instead: each case asserts input is live
(readOnly false), raises the keyboard, then keeps its original
regression intent — the first Back deactivates input and is consumed so
it cannot also pop, and only the second Back pops or cancels.
edde746