A flaw in g-lite's createVec3 function / g-lite 的 createVec3 函数有缺陷

# Chain of invocation / 调用链路

|package 1|package 2|package 3|
|----|----|----|
|@antv/g6|@antv/g|@antv/g-lite|
|Graph.translateBy() → ViewportController.transform()|AdvancedCamera.createLandmark() → AdvancedCamera.gotoLandmark()|Camera.setFocalPoint() / Camera.setPosition() → createVec3()|

When trying to translate the camera to origin, as the coordinate passed to setFocalPoint and setPosition is [0, 0, 0], the `x[1] || y` and `x[2] || z` in createVec3 will malfunction, the values of `y` and `z` will be used instead of `x[1]` and `x[2]`, which will prevent the camera from reaching origin point.

当尝试将相机移动至原点时，由于最终传入 setFocalPoint 和 setPosition 的坐标为 [0, 0, 0] ，createVec3 中的 `x[1] || y` 和 `x[2] || z` 会失效， `x[1]` 和 `x[2]` 被忽略，直接取 `y` 和 `z` ，进而导致无法将相机移动至原点。

# Runtime environment / 运行时环境

- OS: win10
- Browser: WebView2
- Version: g-lite 2.7.0

# Reproduce / 复现

https://stackblitz.com/edit/5lgcknuk?file=index.ts

Start by locating g-lite's createVec3 function and trace its use from Camera.setFocalPoint() and setPosition(). Reproduce the origin-coordinate case with the linked StackBlitz example, then verify that [0, 0, 0] reaches the camera unchanged and add or update coverage for zero-valued coordinates.

Written by the indexing model from the issue text.