fix(reader): keep restore-tip notify flag on tab switch during startup restore

[add-uos]

问题

BUG-376441：打开多个文档并滚动产生阅读进度后关闭文档查看器，再次打开时只有一个文档显示"已恢复到上次阅读位置"提示条，其余标签页永不显示。

根因

启动期多文档恢复时，非可见页签的恢复守卫（beginRestoreGuard(true)）在 onLayoutSettled 中因页签不可见被顺延，m_restoreNotifyTip=true 处于待消费状态。用户首次切到该页签时，CentralDocPage::onTabChanged → DocSheet::restoreSavedViewState() 无条件调用 beginRestoreGuard(false)，把待消费的通知标志覆盖为 false。随后恢复流程正常完成，但 m_needsRestoreTip 永不置位，标签切换时提示条显隐分支永远判 false。

只有启动时恰好可见的活跃标签（上次会话的活跃文档）能在覆盖发生前完成恢复并弹条，与 bug 现象完全吻合。

修复

restoreSavedViewState() 中，若恢复守卫已激活（顺延中的首次恢复），保留其弹条通知标志，仅重启稳定计时等待布局对齐；守卫未激活时保持原有"回切不弹条"行为。

修复后每个有阅读进度的标签页首次切换过去时会恢复滚动位置并弹出提示条；关闭提示条/跳转首页后不再打扰（原有行为不变）。

验证

• 增量编译通过（deepin-reader 与 test-deepin-reader 目标）。
• 详细分析见 .pms/bugs/376441/analysis-report.md。

PMS: BUG-376441

Summary by Sourcery

Bug Fixes:

• Preserve pending restore notifications when switching to tabs during startup document restoration, ensuring each restored document can display its reading-position notification.

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Reviewer's Guide

Fixes startup restoration across multiple tabs by retaining deferred restore-tip notifications during tab switching, while also hardening render-thread shutdown synchronization and making the affected unit test deterministic.

Sequence diagram for preserving restore-tip notifications on tab switch

sequenceDiagram
    participant Startup as StartupRestore
    participant Sheet as DocSheet
    participant Layout as Layout
    participant Tab as CentralDocPage
    participant Timer as RestoreSettleTimer

    Startup->>Sheet: beginRestoreGuard(true)
    Sheet->>Layout: onLayoutSettled
    alt tab is not visible
        Layout-->>Sheet: restore deferred
        Tab->>Sheet: onTabChanged
        Sheet->>Sheet: restoreSavedViewState
        alt m_restoreGuardActive
            Sheet->>Timer: start(kRestoreSettleMs)
            Note over Sheet,Timer: m_restoreNotifyTip remains true
        else guard is inactive
            Sheet->>Sheet: beginRestoreGuard(false)
        end
    else tab is visible
        Layout-->>Sheet: restore completes
    end

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Sequence diagram for safe PageRenderThread shutdown

sequenceDiagram
    participant Main as MainThread
    participant Render as PageRenderThread

    Main->>Render: destroyForever
    Render->>Render: m_quit = true
    Render-->>Main: wait
    Render->>Render: run
    Render->>Render: check m_quit
    Render-->>Main: thread exits

Loading

File-Level Changes

Change	Details	Files
Preserve a pending restore-notification state when a deferred document restore is completed after switching tabs.	Restart the settle timer when an existing restore guard is active, retaining its notification flag. Keep the existing non-notifying behavior when restoring a tab without an active startup guard.	reader/uiframe/DocSheet.cpp
Make render-thread shutdown state safe when destruction races with thread startup.	Use an atomic quit flag for cross-thread access. Stop resetting the quit flag in run(), so an early shutdown request is not lost.	reader/browser/PageRenderThread.cpp reader/browser/PageRenderThread.h
Stabilize the browser-page unit test against headless visibility and shutdown side effects.	Stub visibility and sidebar page updates so the test exercises page-state handling without triggering rendering tasks.	tests/uiframe/ut_docsheet.cpp

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: add-uos, lzwind

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• debian/deepin/OWNERS

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[add-uos]

/merge