Owner: the dashboard button's label under-promised what it does. The
action is a FORCE rescan (scanner.SetForce(true) via the scan worker):
every file re-read and re-extracted with original-scan semantics, hash
identifiers recomputed — the admin's backfill tool, per the scanner's
own source comments. The shallow scans (per-library button, per-folder
scan, processing-issues retry) deliberately skip unchanged files and
keep their 'Scan' labels; the naming now carries that distinction.
Subtitle updated to state the real semantics ('Re-reads every file and
re-extracts metadata and hashes — slow but thorough') instead of the
old 'Re-scan existing files and detect new items', which described the
shallow path. ui-controls.md gains the canonical glossary entry (old
label recorded under also: so anything still quoting it resolves); no
doc quoted the old label yet, so no doc edits were needed.