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.go

@@ -8,6 +8,7 @@ import (
 	tea "charm.land/bubbletea/v2"
 
 	"git.kebcloud.no/keb/lazysecrets/internal/cachefile"
+	"git.kebcloud.no/keb/lazysecrets/internal/expiry"
 	"git.kebcloud.no/keb/lazysecrets/internal/provider"
 	"git.kebcloud.no/keb/lazysecrets/internal/ref"
 	"git.kebcloud.no/keb/lazysecrets/internal/store"
@@ -134,10 +135,10 @@ func (m Model) objectRender() func(styles.Styles, provider.Object, int) string {
 		}
 		line = marks(sty, n, o.Container.Source.Provider, m.recentIcon, m.now()) + line
 		switch state, left := m.expiry(o); state {
-		case expired:
+		case expiry.Expired:
 			line += " " + sty.Error.Render("✗ expired")
-		case expiresSoon:
-			line += " " + sty.Warning.Render("⚠ "+daysLeft(left))
+		case expiry.Soon:
+			line += " " + sty.Warning.Render("⚠ "+expiry.Left(left))
 		}
 		return withNote(sty, line, n.Note, width)
 	}