Fix iPad page-tree resize selection

[Chefski]

Preserves the selected page when a compact iPad page-tree reader transitions to the regular-width detail column.

Verification:

• focused page-presentation unit tests
• focused iPad page-opening UI test
• focused iPad Settings navigation UI test
• strict SwiftLint
• git diff --check

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge with no actionable defects identified.

The new guard aligns selection cleanup with the presentation lifecycle: stack readers clear their matching selection, while detail-column transitions preserve the selected page required after resizing.

Important Files Changed

Filename	Overview
docmostly/Features/PageReader/PageReaderDestinationView.swift	Adds a presentation-aware disappearance guard so compact-to-regular transitions retain the page needed by the detail column.

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[cubic-dev-ai]

No issues found across 1 file

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