refactor(capture): extract virtual feature records

[w1ne]

Summary

• Extract reference image, render environment, camera target, and animation view record construction into src/modeling/capture/virtualFeatureRecords.ts
• Keep CaptureSession responsible for ids, state, and registration only for these virtual features
• Add a byte-stable exported-record contract test and architecture tripwire for the capture session dependencies

Verification

• npm test -- tests/unit/capture/virtualFeatureRecords.test.ts
• npm test -- tests/unit/capture/referenceImage.test.ts tests/unit/capture/renderEnvironmentBridge.test.ts tests/unit/capture/cameraTargetBridge.test.ts tests/unit/capture/animationView.test.ts tests/unit/capture/virtualFeatureRecords.test.ts
• npm run typecheck
• npx eslint src/modeling/capture/captureSession.ts src/modeling/capture/virtualFeatureRecords.ts tests/unit/capture/virtualFeatureRecords.test.ts
• npm test -- tests/unit/kernel/architectureBoundary.test.ts

Subagent review: two reviewers, no findings.