Why: Field evidence - surfaces arrived and tabs opened in state but the
screen showed nothing: the event branch missed syncFilesEntry (right
panel stayed on work tab, collapsed, or list view), refresh/reentry had
no way back (openSurface was dead code), and the files panel listed no
pages.
Evidence: tsc clean; vitest 97/97 including new cases (event switches
rightTab=files + preview view; suppressed path keeps projection
consistent); knip unchanged.
Impact: Frontend-only behavior fixes; no API changes.
Refs: Dev task fix/genui-page-visibility
weichen