fix(qlpreview): hide share-arrow in expired state (gitea#7 review)

The down-chevron above the system Share button is a "tap here"
cue for the active flow. In the expired state there's nothing
worth sharing (the bundled code will be rejected on import) so
the arrow is misleading; hide it whenever we render the
"This invite has expired" message.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

iosApp/HoneyDueQLPreview/PreviewViewController.swift

@@ -288,8 +288,14 @@ class PreviewViewController: UIViewController, QLPreviewingController {
         let expiredAgo = Self.expiredRelativePhraseOrNil(residence.expiresAt)
         if let expiredAgo {
             instructionLabel.attributedText = Self.makeExpiredInstructions(sharedBy: residence.sharedBy)
+            // The down-chevron points at the Share button as a visual
+            // cue to tap it; in the expired state there's nothing
+            // useful to share (the server will reject the bundled
+            // code) so the arrow becomes misleading. Hide it.
+            arrowImageView.isHidden = true
         } else {
             instructionLabel.attributedText = Self.makeResidenceInstructions()
+            arrowImageView.isHidden = false
         }
 
         // Clear existing details