fix: refresh functional icons after theme updates

[biubiukam]

🤔 This is a ...

• New feature
• Bug fix
• TypeScript definition update
• Bundle size optimization
• Performance optimization
• Enhancement feature
• Refactoring
• Update dependency
• Code style optimization
• Test Case
• Branch merge
• Site / documentation update
• Demo update
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🔗 Related issue link

Fixes #4816

💡 Background and solution

Built-in functional icons are regenerated when the theme changes, but HeaderHelper, BodyHelper, and RowSeriesNumberHelper kept the icon objects cached during table initialization. As a result, rebuilding the scenegraph after updateOption(), updateTheme(), or assigning theme continued to use the previous icon colors.

This change adds an updateIcons() method to the three helpers and refreshes their cached icon definitions immediately after applying functional icon colors.

✅ Verification

• npm test -- --runInBand __tests__/functional-icons-theme.test.ts __tests__/listTable.test.ts __tests__/options/listTable-icon.test.ts: 15 tests passed
• npm run compile: passed
• node common/scripts/install-run-rush.js build -t @visactor/vtable: completed successfully with existing build warnings
• The repository-wide pre-push test was also attempted. It remains blocked by unrelated existing failures in vtable-sheet dependency/formula tests and the video-cell-first-frame.test.ts environment tests.

📝 Changelog

Language	Changelog
🇺🇸 English	Refresh built-in functional icon colors after table theme updates.
🇨🇳 Chinese	修复表格主题更新后内置功能图标颜色未刷新的问题。

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

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🚀 Summary

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🔍 Walkthrough

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