fix: resolve 6 Chinese/CJK IME editor issues

[ra3orblade]

Summary

• JS-6963: Inline code/markdown not triggered after CJK characters — extended markdown regex to accept non-ASCII chars as word boundaries
• JS-7213: Chinese search requires space to trigger — added compositionEnd handler to Filter so search updates immediately when IME commits text
• JS-7333 / JS-7558 / JS-8492: Mark position shift / flashing mention icon during IME — use Mark.adjust in onCompositionEnd instead of re-reading marks from DOM HTML, preventing incorrect mark expansion when browsers insert composition text inside mark elements
• JS-9306: Code block scroll jump during Chinese IME — save/restore scroll container position around code block setValue to prevent page jumping during syntax highlight re-render

Not fixed: JS-7120 (WeType extra space) — third-party IME behavior, cannot be resolved in app

Test plan

• Type 你好hello`` in a text block → inline code should render on "hello"
• Open global search, type Chinese characters → results should appear without needing a trailing space
• Create a link in a text block, place cursor before it, type Chinese characters → link underline should stay correctly positioned
• Create inline code, place cursor before it, type Chinese characters → grey background should not shift
• Add a @ mention, type Korean/Chinese after it → mention icon should not flash
• Edit a long code block with Chinese IME, press Enter to commit a character → page should not scroll to top of code block
• Verify bold (**text**), italic (*text*), strikethrough (~~text~~) also work after CJK characters

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