* fix(ibus): restore engine process launch after XDG path import
PR #484 switched ibus_engine to a relative import of xdg_data_home for
Flatpak-safe paths. start_engine_process and the IBus component exec still
run this file by path (python /path/to/ibus_engine.py), which has no
package context, so the process died immediately with ImportError and
Vocalinux fell back to ydotool (clipboard paste).
Accept absolute/inline import fallbacks when loaded as a script, log child
stderr from engine.stderr.log on startup failure, and add a path-based
--xml smoke test so this does not regress.
* test(ibus): cover start_engine_process failure diagnostics
Raise patch coverage for the engine.stderr.log failure paths so
codecov/patch meets the 80% target on #534.
* chore: re-trigger CI after rebase onto main
