fix(qlpreview): inline share icon instead of fixed position (gitea#7 review)

The previous copy "1. Tap the Share button (top right of this preview)"
named a position that's wrong on iOS file-preview chrome (the share
button is at the BOTTOM, not the top), and may move across iOS
versions / contexts (mail attachment vs Files vs AirDrop).

Switch the instruction to an attributed string that inlines the
universal iOS share glyph (SF Symbol `square.and.arrow.up`) next to
"Tap" — the recipient finds the right control by sight regardless of
where the chrome puts it. New `PreviewViewController.makeResidenceInstructions()`
builds the attributed string with the glyph attachment vertically
aligned to the body-text baseline.

`Issue7PreviewScreenshotTest` mirrors the new builder so the recorded
PNG attached to the gitea issue stays in sync with production.

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

iosApp/HoneyDueQLPreview/PreviewViewController.swift

@@ -278,14 +278,13 @@ class PreviewViewController: UIViewController, QLPreviewingController {
 
         titleLabel.text = residence.residenceName
         subtitleLabel.text = "honeyDue Residence Invite"
-        // Numbered steps so non-technical recipients know exactly what to
-        // do. Replaces the prior "Tap the share button below…" which
-        // implied an in-app button and didn't say where the share
-        // control lives (top-right of the QuickLook bar).
-        instructionLabel.text = "How to join:\n"
-            + "1. Tap the Share button (top right of this preview)\n"
-            + "2. Choose \"honeyDue\" from the share sheet\n"
-            + "3. Sign in if prompted — the app finishes the rest"
+        // Numbered steps so non-technical recipients know exactly what
+        // to do. The share button's location varies across the iOS
+        // QuickLook chrome (bottom on file previews, top in mail
+        // previews, sometimes hidden behind a "More" menu) so we lean
+        // on the SF Symbol glyph inline instead of describing a
+        // position that may not match what the recipient sees.
+        instructionLabel.attributedText = Self.makeResidenceInstructions()
 
         // Clear existing details
         detailsStackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
@@ -362,6 +361,60 @@ class PreviewViewController: UIViewController, QLPreviewingController {
         f.timeStyle = .short
         return f
     }()
+
+    /// Builds the "How to join" instruction copy as an attributed
+    /// string with the iOS share-icon glyph (square + up-arrow) inlined
+    /// next to "Tap [icon]". The glyph is the universal share symbol
+    /// across iOS, so the recipient finds the right control whether
+    /// it's at the top, bottom, or behind a More menu — instead of us
+    /// claiming a fixed position the chrome can move (gitea#7 review
+    /// feedback).
+    private static func makeResidenceInstructions() -> NSAttributedString {
+        let bodyFont = UIFont.systemFont(ofSize: 15, weight: .medium)
+        let tint = UIColor(red: 7/255, green: 160/255, blue: 195/255, alpha: 1)
+        let paragraph = NSMutableParagraphStyle()
+        paragraph.lineSpacing = 2
+        paragraph.alignment = .left
+
+        let result = NSMutableAttributedString()
+
+        func appendText(_ s: String) {
+            result.append(NSAttributedString(
+                string: s,
+                attributes: [
+                    .font: bodyFont,
+                    .foregroundColor: tint,
+                    .paragraphStyle: paragraph,
+                ]
+            ))
+        }
+
+        appendText("How to join:\n1. Tap ")
+
+        let shareImage = UIImage(
+            systemName: "square.and.arrow.up",
+            withConfiguration: UIImage.SymbolConfiguration(pointSize: 16, weight: .semibold)
+        )?.withTintColor(tint, renderingMode: .alwaysOriginal)
+        if let shareImage {
+            let attachment = NSTextAttachment()
+            attachment.image = shareImage
+            // Align the glyph baseline with the surrounding text by
+            // nudging the bounds down a few points; the SF Symbol's
+            // natural bounds sit a hair above the cap height.
+            attachment.bounds = CGRect(
+                x: 0,
+                y: -3,
+                width: shareImage.size.width,
+                height: shareImage.size.height
+            )
+            result.append(NSAttributedString(attachment: attachment))
+        }
+
+        appendText("\n2. Choose \"honeyDue\" from the share sheet")
+        appendText("\n3. Sign in if prompted — the app finishes the rest")
+
+        return result
+    }
 }
 
 // MARK: - Type Discriminator