Complete SVG DOM script and interaction runtime lane

[wieslawsoltes]

Complete SVG DOM, Script, And Interaction Runtime Lane

Summary

This PR completes the SVG DOM / Script / Interaction Runtime lane by adding the runtime surfaces and rendering hooks needed for the newly enabled W3C DOM, scripting, interaction, text selection, and static resource coverage.

Changes

• Added SVG JavaScript DOM and CSSOM facades for document, element, event, window, style declaration, animated values, and interaction host APIs.
• Expanded JavaScript runtime behavior for load dispatch, timers, DOM mutation visibility, namespace-preserving element creation, live DOM queries, computed style lookup, cssText, camel-case CSS properties, and viewer scale/translate APIs.
• Added interaction dispatch support for pointer/mouse routing, focus/default actions, cursor changes, hyperlink activation, same-document fragment navigation, and <use> instance hit-node routing.
• Added animation timing support for access-key, wall-clock, event-based begin/end timing, and related controller scheduling behavior.
• Added retained text selection and caret metadata, selection painting, DOM-facing selection APIs, and JavaScript selection bridge coverage.
• Added deterministic broken-image placeholder rendering for invalid, missing, and cyclic nested image resources.
• Hardened nested SVG image loading by forcing static nested documents, handling gzip-compressed SVG data URIs, detecting recursive embedded SVG references, and exposing placeholder settings through Skia asset loading.
• Expanded unit and W3C coverage across JavaScript runtime, interaction dispatch, hit testing, animation timing, text selection, viewer resources, static resource policy, and DOM runtime fixtures.
• Removed the stale struct-image-16-f Chrome override so the W3C row uses the real reference with scoped comparison policy instead of a browser-captured failure state.
• Updated the skipped-test roadmap to document completed runtime-lane coverage and the remaining intentionally skipped policy/browser-only cases.

Validation

• dotnet format Svg.Skia.slnx --no-restore --verify-no-changes
• dotnet build Svg.Skia.slnx -c Release --no-restore
• dotnet test tests/Svg.JavaScript.UnitTests/Svg.JavaScript.UnitTests.csproj -c Release --no-build
• dotnet test tests/Svg.Skia.UnitTests/Svg.Skia.UnitTests.csproj -f net10.0 -c Release --no-build --filter "FullyQualifiedName~SvgInteractionDispatcherTests|FullyQualifiedName~SvgTextSelectionDomTests|FullyQualifiedName~SvgViewerResourceTests|FullyQualifiedName~SvgJavaScriptRuntimeTests"
• dotnet test tests/Svg.Skia.UnitTests/Svg.Skia.UnitTests.csproj -f net10.0 -c Release --no-build --filter "FullyQualifiedName~W3CTestSuiteTests.Tests"
• dotnet test Svg.Skia.slnx -c Release --no-build

The full solution test run passed with Svg.Skia.UnitTests reporting 2442 passed and 16 skipped tests. The build only reports existing package vulnerability warnings from transitive/package references.