Harden Monaco multi-instance and lifecycle contracts

[smiggleworth]

Summary

• document Monaco process-global theme behavior and wrapper-owned path semantics
• cover simultaneous editor theme application and rapid owned-model replacement
• verify async initialization cancellation can safely remount
• record complete production, multi-instance, export, Askr contract, docs, and adversarial lifecycle audits

Validation

• npm run check
• 5 unit tests
• 6 structural checks
• 12 jsdom tests
• 32 browser tests across Chromium, Firefox, and WebKit
• build, publint, and package dry-run inspection
• package version remains 0.2.0

Closes #28
Closes #29
Closes #30
Closes #31
Closes #32
Closes #33
Closes #34

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.