fix(vom): vom support observe iframe

[Ljy-0827]

现有问题

原有 VOM 主要基于顶层文档的 AX Tree 和 DOMSnapshot 构建观察结果，没有完整处理 DOMSnapshot 中的 iframe 子文档及其 AX 节点归属。因此 iframe 内的文本、控件和交互节点无法稳定出现在 VOM 中；当页面存在多个或嵌套 iframe 时，还可能出现节点归属错误、backend node ID 冲突和结构挂载不正确的问题。

解决方案

扩展 VOM 采集和渲染链路，解析 DOMSnapshot 中的 iframe 子文档，并按照明确的 frameId、父 Frame 和 iframe owner 关系组织各 Frame 的 DOM 与 AX 数据。VOM 渲染时保留 Frame 边界，为 iframe 内可交互节点生成有效 ref，同时支持多个及嵌套 iframe。

后续接入

本 PR 是 iframe 观察与录制缺失 issue 的问题拆分，仅解决 iframe 内容进入 VOM 的采集、归属和渲染问题，不引入 OOPIF session 管理和完整的跨 Frame Geometry 机制。

后续 PR 将在此基础上增加 OOPIF target/session 发现、跨 target 数据采集和统一 Geometry，使 iframe 内的 ref 可以进一步用于点击、截图和 help 高亮。后续 PR3 可继续构建统一 VOM 语义图，改善节点命名、结构层级和跨 Frame 语义一致性。

[Copilot]

Pull request overview

This PR extends the VOM (View Observation Model) pipeline to correctly discover, capture, merge, and render iframe / OOPIF content by introducing a CDP-level frame graph, per-frame DOM/AX capture, cross-frame coordinate projection, and frame-aware paint-order comparisons.

Changes:

• Add frame identity fields (frameId/contextScopeId/backendNodeId) to VOM nodes/results and prevent cross-frame handle-context leakage.
• Capture DOMSnapshot + AX trees per frame/target (including OOPIF sessions) and merge them into a single scene with correct parent/owner attachment and top-level coordinate projection.
• Make occlusion/blocking-layer logic frame-aware (paint order is treated as document-scoped; cross-frame comparisons are resolved via iframe owners).

Reviewed changes

Copilot reviewed 26 out of 26 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/vom/src/types.ts	Add per-node frame/backend identity and a richer VomRef; track rootFrameId for paint-order boundaries.
packages/vom/src/render.ts	Enforce contextScope boundaries for handle context; add frame-aware paint-order comparators; emit refs with frameId/backendNodeId.
packages/vom/src/layers.ts	Restrict blocking-layer detection/membership to the root document’s frame paint-order space.
packages/vom/src/index.ts	Re-export VomRef type.
packages/vom/src/tests/render.test.ts	Add tests for context scoping and frame-scoped paint-order blocking behavior.
apps/extension/wxt.config.ts	Raise minimum Chrome version to support flattened debugger sessions for OOPIF.
apps/extension/src/tools/vom/frame-document.ts	Partition/deduplicate AX nodes by frame ownership and cut cross-frame parent edges.
apps/extension/src/tools/vom/frame-capture.ts	Capture missing OOPIF DOM snapshots and per-frame AX trees; build per-frame documents.
apps/extension/src/tools/vom/capture.ts	Track snapshot frameId/ancestry, populate frameNodes maps, and add form value extraction fields.
apps/extension/src/tools/vom/tests/frame-document.test.ts	Validate ownership partitioning, dedupe, and collision handling for frame documents.
apps/extension/src/tools/vom/tests/frame-capture.test.ts	Validate OOPIF DOM capture + top-level projection for multiple child targets.
apps/extension/src/tools/vom/tests/capture.test.ts	Validate frameId propagation and captured frame ancestry outputs.
apps/extension/src/tools/snapshot-ref.ts	Make ref resolution tab-bound and reject iframe-target refs as unsupported (for now).
apps/extension/src/tools/shared.ts	Add target-aware CDP send helpers and extend CdpRunner with optional frame-graph APIs.
apps/extension/src/tools/observation.ts	Route observation through per-frame capture/scene merge; store refs with optional child session identity.
apps/extension/src/tools/frame-geometry.ts	Implement cross-target iframe geometry projection and polygon clipping utilities.
apps/extension/src/tools/tests/snapshot-ref.test.ts	Test rejection of iframe-target refs in resolveSnapshotRef/lookupSnapshotRef.
apps/extension/src/tools/tests/observation.test.ts	Add coverage for multi-frame scene merging and attachment rules.
apps/extension/src/tools/tests/human-loop.test.ts	Update tests to use real RefStore instances with the new ref identity shape.
apps/extension/src/tools/tests/frame-geometry.test.ts	Test projective mapping, polygon clipping, and OOPIF boundary transform behavior.
apps/extension/src/session-manager/ref-store.ts	Store CDP session identity alongside backendNodeId/tabId for refs.
apps/extension/src/session-manager/tests/ref-store.test.ts	Add coverage for persisting child CDP session identity in refs.
apps/extension/src/browser-driver/frame-graph.ts	Introduce frame graph builder that merges multiple frame-tree sources by target boundary.
apps/extension/src/browser-driver/chromium-cdp.ts	Add iframe target auto-attach discovery, recursive session tracking, and frame graph assembly.
apps/extension/src/browser-driver/tests/frame-graph.test.ts	Test frame-graph merging across sibling/nested OOPIFs and deep trees/cycles.
apps/extension/src/browser-driver/tests/chromium-cdp.test.ts	Test multi-session discovery, recursive attachment behavior, and frame graph correctness.

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