feat: share popups draw repos and files like everywhere else

repoLabel draws a repo, or a file in it, with pathLabel: the repo icon
and colour. The share popups use it for what's shared, where it's
from and where it's saved, and are titled for what's shared
("Share .env", "Share 2 env files"), the key picker too.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/ui/app/sharefiles_test.go

@@ -74,7 +74,7 @@ func shareFrom(t *testing.T, root string, paste bool) string {
 				t.Errorf("not a secret: %s", o.label)
 			}
 		}
-		if !strings.Contains(d.screen(), "Encrypt with which secret?") {
+		if !strings.Contains(d.screen(), "Share 2 env files") && !strings.Contains(d.screen(), "Share .env") {
 			t.Errorf("not titled as a picker:\n%s", d.screen())
 		}
 		d.keys("enter")