refactor: drop dead code and use the standard library where it already does the job (#76)

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.

Reviewed-on: #76
Co-authored-by: Karl-Einar Bergstrøm <karl-einarb@outlook.com>

internal/ui/app/favourites_test.go

@@ -14,6 +14,7 @@ import (
 	"git.kebcloud.no/keb/lazysecrets/internal/provider"
 	"git.kebcloud.no/keb/lazysecrets/internal/provider/fake"
 	"git.kebcloud.no/keb/lazysecrets/internal/store"
+	"github.com/charmbracelet/x/ansi"
 )
 
 // jump opens the favourites list, filters it and jumps to the first match.
@@ -429,7 +430,7 @@ func TestStarIsPerAccount(t *testing.T) {
 	d.keys("F")
 	var labels []string
 	for _, o := range d.m.search.shown {
-		labels = append(labels, ansiStrip(o.label))
+		labels = append(labels, ansi.Strip(o.label))
 	}
 	if len(labels) != 1 || !strings.Contains(labels[0], "platform-prod · alice") {
 		t.Errorf("favourites should list alice's star only: %q", labels)