fix(test): retain subprocess coverage and cleanup

[morluto]

Summary

• include boundary and conformance projects in test:fast
• run all split process-ownership suites in the Windows curated lane
• remove failed spawns from the shared process registry on close
• keep testing documentation aligned with the command scope

Verification

• npx vitest run --project boundary tests/boundary/process/processOwnership*.test.ts --reporter=dot (22 passed)
• npx vitest run --project process-global tests/process-global/vitestConfiguration.test.ts --reporter=dot (3 passed)
• npm run typecheck
• npm run check:fast
• Prettier checks passed

The full npm run test:fast was started locally and stopped after initial boundary suites passed because the expanded boundary scope is long-running; CI is the complete gate.

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