[1.x] Product-quality expansion umbrella (app polish, review markup, accessibility, detection breadth)

[mberrys]

Post-1.0 expansion candidates for product quality — the things that make Loop feel like a finished desktop product. None of these gate 1.0; each is intentionally parked here so milestone planning stays clean.

How to use this umbrella

When milestone planning for a 1.x minor starts, promote relevant members out of this umbrella by reopening them, giving them a milestone, and removing their sub-issue link. Do not work members directly against this umbrella issue.

Members (closed, tracked as sub-issues)

• [App quality] Make zoom-to-physical-size correct per display and calibratable #157 zoom-to-physical-size correctness per display (app quality)
• [App quality] Support multiple open documents with tabs, window state, and session restore #158 multiple open documents: tabs, window state, session restore (app quality)
• Extend thin-part detection beyond simple strokes (expand #23) #131 thin-part detection beyond simple strokes (preflight breadth)
• [Review] Add a comments and markup workflow with reply threads, status, and XFDF interchange #168 comments and markup workflow: reply threads, status, XFDF (review)
• [Text editing] Make PDF text editing font-, encoding-, and script-faithful #169 font-, encoding-, and script-faithful PDF text editing
• [Accessibility] Preserve, validate, and produce tagged PDF/UA-conformant output #171 tagged PDF/UA-conformant output (accessibility)

Non-members kept loose on the backlog

Deferred/research items (#47, #54–#57) and small OCR/AI tweaks (#58–#61) remain milestone-less backlog issues; fold them in only if they harden into real scope.