[Eoic]

Crossing an EPUB spine boundary previously waited for the entire destination layout and replaced the page without animation. This change prepares pages incrementally, shares in-flight prefetch work with navigation, and animates forward/backward boundary turns while preserving the committed reading position until the destination is visible.

The bottom bar consistently shows Chapter X of Y · Page X of Y. An explicit ≈ marks estimated totals until a separate yielding counter finishes. Counting does not retain the remaining pages or advance the reading cursor. Geometry changes and disposal cancel both layout and counting work. Reduced motion, queued turns, selection, reflow, and content-offset restoration remain covered.

Closes #9.

Requirements: FR-3_1 and FR-3_2, limited to EPUB navigation and pagination.

Validation:

• 213 reader tests passed, including long single-spine content, shared prefetch, boundary animations, rapid turns, interrupted forward/backward animations, page-count updates, and cancellation.
• Reader analysis, formatting, diff checks, and generated-worker drift check passed.
• Example analysis, 2 example tests, and web build passed.
• 22 focused client reader tests and tools/papyrus check client passed with the existing local reader override.
• Browser smoke covered page turns and keyboard focus. Final focused desktop/mobile browser checks verified exact totals across turns, chapter boundaries, and resizing, with no page errors.

Cold jumps into unmeasured content still require yielding layout work. Continuous scrolling still collects a full layout for its scroll extent. Real-device performance has not been profiled. Client release pins and workspace submodule pointers are unchanged.

Client integration: merged client PR PapyrusReader/client#101 adopted the initial revision. Follow-up PapyrusReader/client#103 pins the interruption review fix at e6c59a7eb238b2088b0b92b25f36b617d63181c1. Merge this reader PR before the follow-up client PR.

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[chatgpt-codex-connector]

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-28T22:33:20.616714Z	865e94a	PR opened

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Reviewed commit: 865e94adff

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