fix(admin): library row button renamed 'Scan' -> 'Force Rescan', per owner

Owner ruling that closed the scan-semantics discussion: the code is
correct (per-library scan IS a force scan — hx-vals force:true since
706be09d), but the label hid that. Now the naming invariant holds
everywhere: anything with Force/Rescan in its name re-reads everything
in its scope; plain 'Scan' only exists at folder scope ('Scan this
folder', shallow) and in auto mode. Book-level Rescan verified as the
per-item force path (extractMetadata re-reads sidecars/tags regardless
of file size; recomputeHashInfo follows) — it is the documented answer
to 'I changed this book's sidecar'.

Glossary Scan entry replaced with Force Rescan (old label kept in also:),
scanning.md table + prose pick up the new label. Generated file
regenerated with the Dockerfile-pinned templ version from inside
templates/ so the diff is exactly the label strings.

docs/developer/ui-controls.md

@@ -218,9 +218,11 @@ does: Force-rescans every library — re-reads each file, re-extracts metadata w
 also: Scan All Libraries
 note: renamed 2026-11-02 — the old label under-promised a heavy operation
 
-label: Scan
+label: Force Rescan
 where: Admin → Libraries → a library's card row
-does: Force-rescans that one library (same semantics as Force Rescan All Libraries, scoped to a single library).
+does: Force-rescans that one library — re-reads and re-extracts every file in it. Same semantics as Force Rescan All Libraries, scoped to a single library.
+also: Scan
+note: renamed 2026-11-02 per owner — the label now carries the force semantics instead of hiding them
 
 label: Scan this folder
 where: Admin → Libraries → a library's panel → a folder row