[hanyu0504]

Summary

• Wait for all active ancestors before executing a DAG join; propagate cancellation to pending task and route callbacks.
• Preserve structured subtask input, validate poll intervals, and redact additional credential keys.
• Remove business payloads from operational logs and refresh English/Chinese integration version references.

The dev workspace commit also removes the duplicate log4j2.properties charset setting. That duplicate is already absent on upstream main, so the PR contains no redundant change to that file.

Verification

• mvn -B -pl workflow-engine -am test (238 tests passed on main)
• mvn -B -pl samples -am '-Dtest=SpringSpnDemoE2ETest' '-Dsurefire.failIfNoSpecifiedTests=false' test (4 Direct E2E tests passed)
• On dev, Direct + Order E2E: 8 tests passed.

Note: the baseline full reactor still has a separate samples SSE terminal-cancel logging assertion failure; not changed in this PR.