[222_100] add inline spell checker

[AnvarAtayev]

Closes Issue #3102

Summary

• add inline spell underlines for misspelled words near the cursor
• store inline spell ranges in a dedicated editor-side spell-error channel
• render squiggly underlines without using the normal selection path
• reuse the existing spell toolbar for click-to-correct behavior
• add the inline spellcheck preference and update the devel note

Testing

• xmake build
• manually enabled Inline spellcheck in Preferences
• verified misspelled words are underlined
• verified clicking a misspelled word opens the spell toolbar
• verified correction removes the underline

Screenshots

• Setting location: Edit > Preferences > Other > Inline spellcheck

• Preview

Screen.Recording.2026-04-04.at.12.24.31.mov

[greptile-apps]

Greptile Summary

此 PR 为 Mogan 编辑器实现了内联拼写检查功能，通过在光标附近的拼写错误单词下方绘制红色波浪线提示，并在点击错误单词时复用现有拼写工具栏。核心实现分为两层：C++ 侧新增 spell_errors_pos（位置观察者数组）及对应的 set/get/clear_spell_errors 接口，Scheme 侧通过串行号机制实现防抖调度，并在 apply_changes 中触发重绘。

整体实现架构合理，位置观察者（position_new/position_delete）确保路径在树修改后仍然有效，析构函数也正确清理了所有位置。先前评审发现的若干问题（THE_SPELL_ERRORS 值冲突、缓冲区切换死代码、工具栏激活时 \"alternate\" 选区被覆盖）仍待处理。

Confidence Score: 4/5

功能实现整体可合并，但先前评审指出的 P1 级 alternate 选区冲突问题尚未修复，建议在合并前处理。

C++ 层的位置观察者管理、重绘逻辑、胶水层绑定均实现正确。但先前评审中发现的三个问题（THE_SPELL_ERRORS 与 ControlMask 值碰撞、缓冲区切换死代码、普通拼写工具栏活跃时 alternate 选区被无条件覆盖）在当前 HEAD 中仍然存在，其中最后一项为 P1 级别，会导致用户在普通拼写检查过程中点击错误单词时丢失当前检查焦点。

TeXmacs/progs/generic/spell-widgets.scm（inline-spell-toolbar-open 中 set-alt-selection alternate 的无条件调用）及 src/Edit/editor.hpp（THE_SPELL_ERRORS 值定义）

Important Files Changed

Filename	Overview
TeXmacs/progs/generic/spell-widgets.scm	新增内联拼写调度、刷新、工具栏触发逻辑；"alternate" 选区无条件覆盖及缓冲区切换死代码等先前已指出的问题尚未修复
src/Edit/Replace/edit_select.cpp	新增 spell_errors_pos 数组的 set/get/clear 实现，使用位置观察者正确追踪路径，析构函数中调用 clear_spell_error_positions 释放资源，逻辑无误
src/Edit/Interface/edit_repaint.cpp	新增 draw_spell_error_wave 函数及 apply_changes 中的双阶段（先失效旧矩形、再计算新矩形）更新逻辑，波浪线绘制与现有选区渲染路径正确分离
src/Edit/Interface/edit_interface.cpp	在 apply_changes 中正确处理 THE_SPELL_ERRORS 变更标志，先失效旧矩形再重建新矩形，与 alt_selection_rects 的处理模式一致
src/Edit/editor.hpp	新增 THE_SPELL_ERRORS = 1024，与同文件可见的 ControlMask = 1024 数值重叠，先前评审已指出但尚未修复
TeXmacs/progs/texmacs/menus/preferences-widgets.scm	"Inline spellcheck" 设置被添加到 other-preferences-widget 和 experimental-preferences-widget* 两个组件中，同一设置在首选项对话框中可能出现两次

Sequence Diagram

sequenceDiagram
    participant User
    participant Scheme as spell-widgets.scm
    participant Glue as Glue Layer
    participant Cpp as edit_select_rep (C++)
    participant Repaint as edit_interface_rep

    User->>Scheme: 按键 / 鼠标点击
    Scheme->>Scheme: schedule-inline-spell-underlines<br/>(串行号防抖, idle 350ms/900ms)
    Scheme->>Scheme: inline-spell-current-word()<br/>tree-spell-at → sels
    alt sels 非空
        Scheme->>Glue: (set-spell-errors sels)
        Glue->>Cpp: set_spell_errors(range_set)
        Cpp->>Cpp: clear_spell_error_positions()
        Cpp->>Cpp: position_new() × N
        Cpp->>Repaint: notify_change(THE_SPELL_ERRORS)
    else sels 为空
        Scheme->>Glue: (clear-spell-errors)
        Glue->>Cpp: clear_spell_errors()
        Cpp->>Repaint: notify_change(THE_SPELL_ERRORS)
    end
    Repaint->>Repaint: apply_changes()<br/>失效旧 spell_error_rects
    Repaint->>Cpp: get_spell_errors()
    Cpp->>Repaint: resolve_spell_errors() → range_set
    Repaint->>Repaint: 重建 spell_error_rects<br/>draw_spell_error_wave()

    User->>Scheme: 鼠标左键释放 (release-left)
    Scheme->>Scheme: inline-spell-underlines-refresh()
    Scheme->>Scheme: inline-spell-show-toolbar-at-cursor()
    Scheme->>Scheme: inline-spell-toolbar-open(sel)<br/>set-alt-selection "alternate"
    Scheme->>Scheme: spell-focus-on(sel)<br/>显示拼写建议工具栏

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_{Reviews (2): Last reviewed commit: "[222_100] add inline spell checking" | Re-trigger Greptile}

[MoonL79]

The overall layering here looks reasonable, but I think there are two behavioral gaps that should be addressed. First, inline spell recomputation is currently tied mainly to
keyboard-press, keyboard-focus, and mouse release events. That means many other document-changing paths do not trigger a fresh spell scan, such as undo/redo, paste, replace,
toolbar/menu-driven edits, or other programmatic tree updates. On the C++ side, a THE_TREE change only causes the existing spell ranges to be re-resolved into rectangles and
repainted; it does not ask Scheme to recompute misspellings. As a result, it is easy for the underline state to become stale after the document content has already changed.

Second, disabling "spell underlines" does not fully clear state across all views. clear-inline-spell-underlines only calls clear-spell-errors when there is a current-view,
but the underline state itself is stored per editor/view instance. In a multi-window setup, this means turning the global preference off clears the active window, while
stale squiggles can remain visible in other open views until they happen to refresh on their own. I think the clear/refresh path needs to cover all relevant views; otherwise
the behavior does not really match the semantics of a global preference.