003-B08: finalize usage and evaluate reports

[alexdeem]

Summary

• finalize concurrent executions into one immutable usage, diagnostic, cleanup, and recording-health result
• add explicit attachment-scoped evaluation and deterministic safe report rendering
• consolidate sequential lease closure into @discardableResult close() -> SequentialTrackUsage
• prove cancellation, cleanup, reporter lifetime, freeze races, usage accounting, and random-system finalization
• mark plan unit 003-B08 accepted and record its refreshed verification evidence

Verification

• scripts/check (78 tests; formatting, strict lint, warnings-as-errors debug tests, release build)
• scripts/coverage swiftpm macos
• scripts/coverage ios on iPhone 17 / iOS 27.0 with the iOS 18 deployment floor
• pinned x86_64 Swift Linux Apple Container coverage reproduction
• negative compiler probe confirming ScenarioExecution.finish() remains nondiscardable
• git diff --check master...HEAD

Local Apple verification used Xcode 27.0 final (27A266a) and Apple Swift 6.4 (swiftlang-6.4.0.34.1).

[codecov]

Codecov Report

❌ Patch coverage is 96.21849% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.80%. Comparing base (65fb870) to head (9ba73cd).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
Sources/DioramaCore/ScenarioReportRendering.swift	91.01%	8 Missing ⚠️
Sources/DioramaCore/ExecutionUsage.swift	97.44%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #17      +/-   ##
==========================================
- Coverage   97.84%   97.80%   -0.04%     
==========================================
  Files          13       17       +4     
  Lines         602      819     +217     
==========================================
+ Hits          589      801     +212     
- Misses         13       18       +5     

Flag	Coverage Δ
ios	97.68% <96.22%> (-0.16%)	⬇️
linux	97.80% <96.22%> (-0.04%)	⬇️
macos	97.68% <96.22%> (-0.16%)	⬇️

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