fix(capture): sample forced states in one CDP session

[BenSheridanEdwards]

Why does this feature exist?

StyleProof 4.7.3 flushed forced pseudo-state transitions in one CDP session but sampled the subtree through a separate Playwright session. Hydrated applications could therefore report intermittent phantom hover and active changes on unchanged controls.

What changed?

• Sample the base and forced computed-style subtree through the same CDP session that applies the pseudo-state.
• Fail loudly if the in-session snapshot raises a browser exception.
• Repeat the forced-state regression across eight independent captures.
• Release the correction as 4.7.4 and document it in the changelog.

Behavioural Proof (with video and screenshots)

• Video: Not applicable; this is a non-visual capture-engine synchronization fix.
• Screenshots: Not applicable; generated screenshots would not independently prove protocol-session correctness.
• Behaviour tests: The focused Chromium regression completed eight independent forced-state sweeps and asserted byte-equivalent maps while preserving hover, focus-visible, and active deltas for every one of 24 controls. Full prepublish verification passed: 631 unit tests and 117 browser tests.

Verification Summary

• Definition of Done: followed .agents/project/DEFINITION_OF_DONE.md.
• Commands run: npm run prepublishOnly; the repository commit and push hooks also ran build, typecheck, lint, format, privacy, fallow, gitleaks, and the unit suite.
• Results: 631 unit tests passed; 117 Chromium tests passed; zero failures.
• Known risks or skipped checks: No checks skipped. Adopters should regenerate affected baselines because previously captured forced-state values may contain false deltas.

Checklist

• Proof above — linked the regenerated docs/demo/report.md, or pasted the command/test output that demonstrates the change
• If you changed capture/diff/report rendering, ran npm run demo:report and committed docs/demo/ (not applicable: rendering unchanged)
• npm run build && npm run typecheck && npm run lint && npm run format:check pass
• npm test passes (and npm run test:e2e if the capture/engine path changed)
• Added/updated tests for the change
• Updated the README / CHANGELOG if behaviour or the public API changed
• If captured output changed, noted that adopters must regenerate baselines
• Followed .agents/project/DEFINITION_OF_DONE.md and .agents/skills/pr-inline-screenshot-proof/SKILL.md
• Screenshots are committed and embedded inline, or the proof section says Not applicable with the technical reason
• The PR body has no bare screenshot links, local paths, relative paths, or proof placeholders

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Coverage, determinism, or report/diff consistency evidence is incomplete — repair the capture or reflow source; visual approval cannot clear this failure.