fix(admin): rename 'Scan All Libraries' to 'Force Rescan All Libraries'

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.

templates/admin.templ

@@ -77,9 +77,9 @@ templ Admin(user User, stats AdminStats) {
 							<button @click="scanAllLibraries()" class="btn btn-primary py-4 flex-col items-start gap-1">
 								<span class="flex items-center gap-2 font-medium">
 									@Icon("refresh", "h-5 w-5")
-									Scan All Libraries
+									Force Rescan All Libraries
 								</span>
-								<span class="text-xs font-normal opacity-80">Re-scan existing files and detect new items</span>
+								<span class="text-xs font-normal opacity-80">Re-reads every file and re-extracts metadata and hashes — slow but thorough</span>
 							</button>
 							<a href="/admin/library" class="btn btn-secondary py-4 flex-col items-start gap-1">
 								<span class="flex items-center gap-2 font-medium">

templates/admin_templ.go

@@ -167,7 +167,7 @@ func Admin(user User, stats AdminStats) templ.Component {
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}
-		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 15, "Scan All Libraries</span> <span class=\"text-xs font-normal opacity-80\">Re-scan existing files and detect new items</span></button> <a href=\"/admin/library\" class=\"btn btn-secondary py-4 flex-col items-start gap-1\"><span class=\"flex items-center gap-2 font-medium\">")
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 15, "Force Rescan All Libraries</span> <span class=\"text-xs font-normal opacity-80\">Re-reads every file and re-extracts metadata and hashes — slow but thorough</span></button> <a href=\"/admin/library\" class=\"btn btn-secondary py-4 flex-col items-start gap-1\"><span class=\"flex items-center gap-2 font-medium\">")
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}