Replaces the leaky per-element package check and the keyboard-region Y
heuristic with one rule: walk the window tree propagating each node's owning
package (empty and the neutral android framework package are transparent); a
node is in scope only when no concrete foreign package owns it (the app's own
window carries no package on Compose apps) or the owner is the app package.
This drops whole foreign windows (soft keyboard, system UI, launcher) AND
their empty-package child wrappers -- e.g. a keyboard's 'Settings' key, which
the old empty-package-is-in-scope rule admitted and which navigated out of the
app. Deletes keyboardRegionTop/isInputMethodElement.
The full-screen IME decor view rejection had no test; removing it left the
suite green. Add direct cases: no keyboard -> sentinel, decor view ignored in
favor of the real keyboard line, and decor-only -> sentinel.
A zero-bounds element centers at (0,0); a downward swipe from the
top-left corner is the system gesture that pulls down the notification
shade, dragging the fuzzer out of the app. Swipes now require positive
bounds like every other verb.
pj