fix: support rendering into ShadowRoot containers

[xxMudCloudxx]

原因应该是在 renderer 中：Renderer.render() 先把SVG设成 visibility: hidden ，然后它是通过 MutationObserver 来恢复的，但是这个 observer 只监听了 document ，所以 document 上的 MutationObserver 看不到 ShadowRoot 内部的新增节点，所以 postRender() 没有执行，结果就是 removerProperty("visibility") 没有执行。

fix：#222

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

此拉取请求旨在解决当渲染目标位于 ShadowRoot 内部时，渲染器无法正确完成渲染过程的问题。通过修改容器解析逻辑和 MutationObserver 的观察机制，现在可以确保在 ShadowRoot 环境下，SVG 元素的可见性能够被正确恢复，从而提升了组件在复杂 Web 组件环境中的兼容性和稳定性。

Highlights

• ShadowRoot 容器支持: 现在支持将 ShadowRoot 实例作为渲染容器，扩展了组件的部署灵活性。
• 增强的容器解析: 改进了容器解析逻辑，使其能够识别并解析 ShadowRoot 内部的元素选择器，确保即使在封装的 DOM 环境中也能找到正确的渲染目标。
• MutationObserver 行为优化: 调整了 MutationObserver 的观察目标和 subtree 选项，以正确处理 ShadowRoot 中的节点添加事件，解决了渲染器在 ShadowRoot 环境下无法完成渲染的问题。

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[gemini-code-assist]

Code Review

这个 PR 旨在支持将图表渲染到 ShadowRoot 中，这是一个很棒的功能增强。整体实现思路是正确的，通过修改容器解析逻辑来查找 Shadow DOM 中的元素，并调整 MutationObserver 的观察目标。

代码审查发现了一些可以改进的地方：

1. 在 renderer.ts 中，MutationObserver 的 subtree 选项被错误地设置为 false，这可能导致在某些情况下 SVG 无法被正确检测到。
2. 同样在 renderer.ts 中，getObservationTarget 函数存在冗余代码。
3. 测试代码中存在一些不正确的类型转换和可以简化的实现。

我已经对这些问题提出了具体的修改建议。修复这些问题后，代码将更加健壮和清晰。

[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 46.29%. Comparing base (31e571d) to head (a1b42ee).

Files with missing lines	Patch %	Lines
src/renderer/renderer.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #223   +/-   ##
=======================================
  Coverage   46.29%   46.29%           
=======================================
  Files         341      341           
  Lines       28109    28109           
  Branches     2310     2310           
=======================================
  Hits        13014    13014           
  Misses      15083    15083           
  Partials       12       12           

Flag	Coverage Δ
infographic	46.29% <50.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/options/parser.ts	93.26% <100.00%> (ø)
src/options/types.ts	100.00% <ø> (ø)
src/renderer/renderer.ts	76.16% <0.00%> (ø)

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[xxMudCloudxx]

为了避免“字符串 selector 穿透 Shadow DOM”的扫描成本只能遵循以下准则：

• 普通 DOM 支持 container: '#id'
• Shadow DOM 场景请直接传 Element 或 ShadowRoot

[xxMudCloudxx]

渲染问题解决了，但是还存在一个编辑器的问题：
当设置 editable: true 且信息图位于 Shadow Tree 内部时，插件UI（如 EditBar 和 ResetViewBox）会渲染在组件外部，不再属于同一个 Shadow 边界。因此，尽管 API 现在可以接受 ShadowRoot 作为容器，但内置的编辑 UI 会出现错位或失效的问题。
晚点我修下~

[xxMudCloudxx]

针对编辑器的ShadowRoot修改比较多，我拆成一个新的pr提交 #224 ，这个pr应该可以了