Summary

• add a post-event data loader dispatch lifecycle callback to release subscription event call stacks after the event result completes
• clean up alternative call context naming so it covers both deferred execution and subscription event execution
• add regression coverage for per-level and exhausted dispatch strategies plus subscription integration coverage

Fixes #4314

Verification

• ./gradlew test (5603 tests, 8 skipped)

Note: an initial non-clean full-suite run failed in JMHForkArchRuleTest due stale build output; after ./gradlew clean test --tests graphql.archunit.JMHForkArchRuleTest passed, a clean full ./gradlew test passed.