fix(marker): respect markLine z2 for labels. close #21650

[jesco-absolut]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Makes markLine labels follow the same item z2 ordering as their corresponding markLine graphic.

Fixed issues

• [Bug] Markline z2 is not effect on label #21650: markLine.data[].z2 affected the line but not the label, so labels could render above higher-z2 markLines.

Details

Before: What was the problem?

markLine item z2 was applied to the line path, but the attached label received the default text-content z2 lift from traverseUpdateZ.

That meant a lower-z2 markLine label could still be rendered above a higher-z2 markLine. In the reported case, two markLines with different z2 values ordered their lines correctly, but their labels did not follow the same ordering.

After: How does it behave after the fixing?

traverseUpdateZ now supports a configurable label z2 lift while preserving the existing default behavior.

MarkerView uses a zero label lift for markLine, so the label keeps the same z2 ordering as the markLine item. markPoint and markArea keep the previous default label lift behavior.

A visual case was added to test/marker-z-z2.html where two overlapping markLines use z2: 1 and z2: 2; the blue z2: 2 line and label should render above the red z2: 1 label.

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/marker-z-z2.html

Merging options

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

Other information

Validation run locally:

• npm run checktype
• npm run build
• npx eslint src/util/graphic.ts src/component/marker/MarkerView.ts
• git diff --check

No dist/ files are included in this PR.

[echarts-bot]

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