1) Scan only the MAPPED libraries — never fall back to 'all'. The scan path used
_sections/_views with the selected name, but an empty name returned ALL sections
of that type — so a missing/unreadable selection silently scanned every library
(how the 4K movie + 'YouTube' TV libraries leaked in as movies/shows). New
_scan_sections / _scan_views return [] when a kind isn't mapped; available_libraries
still lists all (for the Settings dropdown). Now an unmapped kind scans NOTHING.
2) A library scan (full/incremental/deep) now pauses EVERY enricher, including the
YouTube date enricher — a separate singleton outside engine.workers that kept
running through scans. pause_for_scan/resume_after_scan pause+resume it too, only
if it wasn't already manually paused (never override the user).
kettui: source-scope tests (mapped-only / unmapped-scans-nothing / listing still
shows all) + engine pause tests (pauses+resumes YT / preserves manual pause).
123 scanner/source/enrichment tests + isolation guard green.
7cd289e7b5