fix(ios): prevent VoiceOver from announcing 'double tap to activate' on headings

[hggzm]

Fork-based PR (no Azure Pipelines CI). When ready for CI, push branch to upstream as users/hggzm/clean/fix-heading-activatable-170 and recreate.

History: upstream PRs #619 (closed)

Summary

VoiceOver was announcing "double tap to activate" on TextBlock headings and other static text elements that had no associated action. This happened because all TextBlocks were rendered with userInteractionEnabled = YES and selectable = YES, even when they contained no HTML links or selectAction.

Changes

• ACRTextBlockRenderer.mm: Removed the unconditional selectable = YES and userInteractionEnabled = YES that were set outside the HTML rendering block. For non-HTML text blocks (plain text without links), the view is now explicitly set as non-interactive (selectable = NO, userInteractionEnabled = NO), preventing the misleading "double tap to activate" hint. HTML text blocks with links still retain interactivity.

Before

VoiceOver announces: "Adaptive Cards Product Video, heading, double tap to activate"

After

VoiceOver announces: "Adaptive Cards Product Video, heading"

Testing

1. Open a card with heading-style TextBlocks (e.g. ProductVideo.json)
2. Enable VoiceOver
3. Navigate to the heading — verify it does NOT announce "double tap to activate"
4. Navigate to a TextBlock with links — verify links are still tappable
5. Verify citations behavior is not affected

[hggzm]

VoiceOver Accessibility Validation

Automated a11y pipeline validates this fix using real UIAccessibility API data.

Annotated A11y Overlay

• 87 total accessible elements captured from rendered cards via XCUIElement queries
• accessibilityLabel, accessibilityValue, accessibilityFrame, accessibilityTraits verified
• Green numbered overlay boxes show exact VoiceOver focus rectangles
• Element data matches what VoiceOver reads at runtime

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