Add legacy web renderer debugger bridge

[bjdodson-openai]

Description

Bridges the debugger to Snap's existing legacy web renderer without requiring the unrelated renderer/runtime rewrite.

• Uses backing-node traversal with bounded, getter-safe serialization.
• Keeps embedded pages isolated and retained handles inert after teardown.
• Adds adversarial liveness, mutation, Unicode, depth, and envelope coverage.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• Documentation improvement
• Performance optimization
• Test improvement
• Other (new debugger capability)

Testing

• Tests pass locally (bazel test //...)
• Added/updated tests for changes (if applicable)
• Tested on multiple platforms (iOS/Android/Web/macOS as applicable)
• Manual testing performed (describe below)

Testing Details

• Incremental branch: Focused web-renderer Bazel suite passed 85/85; pinned TypeScript, runtime probes, formatting, and diff checks passed.
• Assembled debugger stack: npm test passed 436/436; the CLI production build passed.
• Focused //src/valdi_modules/src/valdi/web_renderer:test passed.
• bazel query //... passed.
• The broad Valdi suite reproduced the established 12 unrelated failures; all new debugger specs passed.

Checklist

• Code follows project style guidelines
• Documentation updated (if needed)
• No breaking changes (or documented in description)
• Commit messages follow conventional format
• No secrets, API keys, or internal URLs included

Related Issues

Relates to #154

Additional Context

Stack 4/22. Stacked on #156 (bjd/debugger-input). Review this PR as the single incremental commit 6f465ec0 against that base; do not merge it before its parent.

[github-actions]

📊 PR Size: size/XL

Total changes: 2183 lines (7 files)

Top files changed:

• src/valdi_modules/src/valdi/web_renderer/test/LegacyWebDebuggerAdapter.spec.ts: +909 -0
• src/valdi_modules/src/valdi/web_renderer/src/ValdiWebRendererDelegate.ts: +626 -4
• src/valdi_modules/src/valdi/web_renderer/test/WebDebuggerBridge.spec.ts: +314 -0
• src/valdi_modules/src/valdi/web_renderer/src/debug/WebDebuggerBridge.ts: +275 -0
• src/valdi_modules/src/valdi/web_renderer/test/LocationQuery.spec.ts: +30 -0
• src/valdi_modules/src/valdi/web_renderer/src/utils/LocationQuery.ts: +21 -0
• src/valdi_modules/src/valdi/web_renderer/src/ValdiWebRenderer.ts: +4 -0

_{Size calculated as additions + deletions. Labels: XS (<10), S (<50), M (<250), L (<1000), XL (1000+)}

[github-actions]

⚠️ Bazel & CI Test Results

Test Suite	Result
Snapshot Tests	✅ success
Test Coverage Delta	✅ success
Valdi Smoke Tests	✅ success
API Surface Check	✅ success
Linux: C++ Tests	✅ success
Linux: Registry Validation	✅ success
Linux: Build Compiler	✅ success
Linux: Module Tests	✅ success
Linux: Build & Export	✅ success
valdi_web Integration Test	✅ success
Linux: Hotreload Smoke	✅ success
macOS: C++ & Platform Tests	❌ failure

Some tests failed. Please check the workflow logs for details.

🚀 Bazel remote cache is now enabled - future builds will be faster!

_{Workflow: Valdi CI}