[Bug] [Treemap] Label vertical alignment is broken when `style.height` is set by `beforeUpdate` with `lineOverflow: 'truncate'`

[zhoumutou]

Version

5.4.2 (also confirmed in 5.6.0 source, not fixed)

Link to Minimal Reproduction

https://codepen.io/zhoumutou/pen/vEgWrRo

Steps to Reproduce

1. Create a treemap with ~20+ leaf nodes (many small blocks) and 2-level hierarchy (groups with children)
2. Use a rich-text label with 3 lines (e.g. dimension name, main value, minor value) and overflow: 'truncate'
3. Use a labelLayout callback to vertically center the label:

labelLayout(params) {
  const { rect, labelRect } = params
  return {
    y: rect.y + (rect.height - labelRect.height) / 2,
    align: 'center',
    verticalAlign: 'top'
  }
}

### Current Behavior

Labels in large blocks are approximately centered (off by ~3px), but labels in small blocks are significantly misaligned — they appear near the top of the block or offset, not centered.

### Expected Behavior

Labels should be vertically centered in each treemap block, regardless of block size.

### Environment

```markdown
ECharts: 5.4.2
zrender: 5.4.4
Browser: Chrome 126+

Any additional comments?

Suggested fix
The core issue is that style.height serves dual purposes:

Truncation boundary (intended)
outerHeight for vertical alignment (unintended side effect)
Possible approaches:

In parseRichText, use contentHeight (actual text height) for outerHeight instead of style.height, and only use style.height for truncation
Or: provide the truncated labelRect.height to the labelLayout callback (compute it after beforeUpdate)
Or: in TreemapView.beforeUpdate, don't set style.height — use a separate property for truncation boundary

[helgasoft]

small blocks are significantly misaligned — they appear near the top of the block or offset, not centered.

It seems this is by design, same in current v.6. Label legibility is given priority over positioning. It's better to see partial labels of small blocks than not see them at all if centered.
Demo - t2 is a small block with a vertically truncated label; clicking on t11 or t66 above will give more space to t2 block and show the entire label.