Gateway users can now search resumable sessions from messaging surfaces:
/sessions search <query> (alias: find) matches titles and session ids —
including every title/id in a row's forward compression chain, so a
compressed-away title still surfaces its live tip — plus a
punctuation-normalized variant so 'an94' matches 'AN-94'.
Implemented by generalizing the existing id_query chain-filter in
SessionDB.list_sessions_rich into a combined SQL-level filter (search
stays ORDER BY last-active + LIMIT at SQL level), threading a
search_query through the shared query_session_listing helper, and
teaching parse_session_listing_args to split off a search query.
Search results pass through the existing _resume_row_visible guard
unchanged: origin scoping, admin-only 'all', and the fail-closed
legacy-row posture from the July 1 hardening are preserved exactly.
Over-fetch (50) before the visibility cut so origin-invisible matches
can't starve the page.
Salvages the feature direction of PR #57595 by @GodsBoy with a minimal
implementation that keeps the resume authorization surface untouched.
