refactor: drop dead code and use the standard library where it already does the job

No behaviour change.

- Deleted, unused or one-line wrappers: panes.RuneIndexes, Detail.Refresh (SetDescribed does it), SecretValue.Len, Query.Empty, Clipboard.Native, config.Load, get's value, Model.done, providerOf (cachefile.ProviderOf), contextWithTimeout, searchCoverage, startCrawl, showKeybindings, the expiry aliases and daysLeft.
- cmp.Or instead of the two cmpOr copies; slices.Sorted(maps.Keys(…)), maps.Copy, wg.Go, utf8.RuneCountInString and new(true) instead of loops and helpers that do the same.
- A container's pane title is set once, not twice; a redundant length check in share links and a no-op assignment in linkhandler.Launch are gone.
- Tests call ansi.Strip and lastLines directly; gofmt -s on links.go.

internal/ui/panes/detail.go

@@ -60,16 +60,6 @@ func (d *Detail) ShowSecret(s provider.Object) {
 	d.container = &s.Container
 }
 
-// Refresh shows s's newer metadata if s is the secret shown, keeping
-// its account and any value shown or loading.
-func (d *Detail) Refresh(s provider.Object) {
-	if d.secret == nil || d.secret.ID != s.ID {
-		return
-	}
-	s.Container = d.secret.Container
-	d.secret = &s
-}
-
 // ShowContainer shows a container summary when no secret is selected.
 func (d *Detail) ShowContainer(c provider.Container) {
 	d.Clear()