[codex] Fix global environment concurrency

[hainayanda]

Problem

GlobalValues resolved instances while holding the registry lock. A resolver configured with resolveOn: could synchronously hop to another queue, access another global value, and deadlock waiting for the lock still held by the calling thread.

Moving assignment notifications outside synchronization also allowed delayed notifications to refresh observers with stale resolvers.

Solution

• Snapshot registered resolvers under the recursive registry lock, then resolve them after unlocking.
• Add per-key assignment revisions and filter notifications that are no longer current.
• Keep Combine delivery outside the registry lock.
• Restore independent synchronization for GlobalEnvironment state.
• Simplify macro-generated getters to rely on the synchronized GlobalValues subscript.

Impact

resolveOn: resolvers can safely access other global values without cross-thread deadlocks, and observers ignore delayed stale assignment notifications. Public API behavior remains unchanged.

Validation

• xcrun swift test (23 tests passed)
• git diff --check

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 0 complexity · 0 duplication

Metric	Results
Complexity	0
Duplication	0

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