fix(visualMap): retain string type for raw categories to avoid precision loss (#21714)

[Raman-Katiyar]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Retains string type for raw categories in visualMap during evaluation to prevent precision loss on large integer strings.

Fixed issues

• [Bug] visualMap categories 包含大整数字符串时被错误转换为 Number 导致散点颜色不显示 #21714: Large string categories fail to map visually due to number conversion precision loss.

Details

Before: What was the problem?

When large integer strings (e.g., '6053822903760037657') are passed as categories in visualMap, converting them to numbers causes precision loss, causing visual mapping and rendering to fail.

After: How does it behave after the fixing?

The raw string type is preserved during visualMap evaluation in applyVisual, maintaining exact category matching and rendering the chart items correctly.

Document Info

One of the following should be checked.

• This PR doesn't relate to document changes
• The document should be updated later
• The document changes have been made in apache/echarts-doc#xxx

Misc

Security Checking

• This PR uses security-sensitive Web APIs.

ZRender Changes

• This PR depends on ZRender changes (ecomfe/zrender#xxx).

Related test cases or examples to use the new APIs

test/test_bug21714.html

Merging options

• Please squash the commits into a single one when merging.

Other information

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