[codex] Remove Chary dependency

[hainayanda]

Problem

Chary is deprecated and its safeSync helper is no longer a suitable dependency for SwiftEnvironment.

Solution

• Remove Chary from the SwiftPM manifest and library target.
• Add an internal DispatchQueueExecutor that uses queue-specific context to avoid nested synchronous dispatch deadlocks.
• Update global environment access and instance resolvers to use the internal executor.
• Handle main-thread execution directly in GlobalEnvironment.
• Add a regression test covering nested synchronization on the configured queue.

Impact

Consumers no longer transitively depend on Chary. Existing resolver queue behavior remains intact while nested queue access stays deadlock-safe.

Validation

• xcrun swift build
• xcrun swift test (20 tests, 0 failures)
• git diff --check
• Confirmed swift package show-dependencies only lists swift-syntax

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 0 complexity · 3 duplication

Metric	Results
Complexity	0
Duplication	3

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Clear queue-specific data before releasing the key

When a resolver is replaced or deallocated while its supplied queue remains alive, this executor releases specificKey without removing the queue's associated value. DispatchSpecificKey identities can then be reused by a later executor, causing getSpecific to find the stale value while running on the old queue and incorrectly execute work inline instead of synchronously on the newly configured queue. This can violate resolveOn: isolation, including running main-queue work off-main; clear the specific value from queue before the key is destroyed.

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