Add AdaScript async tasks, awaits, and suspension policy

[SpectralDragon]

Summary

• Add AdaScript async tasks and awaits backed by Gravity fibers and an AdaEngine-owned scheduler.
• Support background asset loading, atomic and streamed saves, game/real-time timers, promises, and AdaUI continuations.
• Add @nonsendable suspension policy for script and native bridge values; validate callback contracts without name-based heuristics.
• Remove the Swift textual async lowerer and pin the native Gravity compiler revision 24695757a0ba5638b3633004a2166b7878c116de.

Validation

• AdaScripting suite with the native Gravity tree: 102 tests passed.
• Async suite with the published pinned Gravity revision: 20 tests passed.
• Normal-manifest swift build --target AdaScripting passed; focused strict SwiftLint passed.
• Gravity virtual machine suite: 9 tests passed in the dependency branch.

Review order and limits

Review Gravity PR #5 first. ADR-0015 records remaining VM trap isolation, broader static @nonsendable analysis, and platform runtime validation. This PR is a draft until those release gates are resolved.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-24T13:49:13.052758Z	edb2ffe	Draft marked ready

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