feat: add orchestration state status predicates

[wangbill (YunchuWang)]

Summary

What changed?

• Add getter-only OrchestrationState.isRunning and isCompleted, computed from the current mutable runtimeStatus.
• isRunning is true only for RUNNING. isCompleted is true only for COMPLETED, FAILED, or TERMINATED: completion does not imply success. PENDING, SUSPENDED, CONTINUED_AS_NEW, and CANCELED return false for both.
• Add status-table, mutation, and getter-only regression tests plus core release notes. No constructor, enum, query, lifecycle, provider, or HTTP changes.

Why is this change needed?

• Before: callers repeat status comparisons. After: they can read the two predicates directly, matching .NET OrchestrationMetadata at d0191fa.

Issues / work items

• N/A.

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Project checklist

• Release notes are not required for the next release
  • Otherwise: Notes added to CHANGELOG.md
• Backport is not required
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• All required tests have been added/updated (unit tests, E2E tests)
• Breaking change?
  • If yes:
    • Impact: N/A; additive concrete-class getters.
    • Migration guidance: N/A.

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AI-assisted code disclosure (required)

Was an AI tool used? (select one)

• No
• Yes, AI helped write parts of this PR (e.g., GitHub Copilot)
• Yes, an AI agent generated most of this PR

If AI was used:

• Tool(s): GitHub Copilot.
• AI-assisted areas/files: Core state getters, their unit tests, and CHANGELOG.md.
• What you changed after AI output: Agent self-review and automated verification only; no human review is claimed.

AI verification (required if AI was used):

• I understand the code and can explain it
• I verified referenced APIs/types exist and are correct
• I reviewed edge cases/failure paths (timeouts, retries, cancellation, exceptions)
• I reviewed concurrency/async behavior
• I checked for unintended breaking or behavior changes

Human attestations above are intentionally left for the reviewer.

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Testing

Automated tests

• Result: Passed. TDD RED: 12 new tests failed at runtime for missing predicates while 10 existing tests passed. GREEN: 40/40 tests across orchestration-state.spec.ts, new-orchestration-state.spec.ts, and test-client-serialization.spec.ts.
• npm run build:core and a public declaration consumer type-check passed, including boolean reads, rejected writes, and the client return type.
• Scoped ESLint and git diff --check passed. Added-code Prettier comparison passed against the base; two pre-existing wrapping differences remain untouched, and CRLF is preserved.
• Broad suites, sidecar/Azure tests, and hosted CI were not run locally.

Manual validation (only if runtime/behavior changed)

• Environment (OS, Node.js version, components): Windows, Node.js v24.14.0; local core SDK only.
• Steps + observed results: N/A; the pure computed getters are covered by automated checks for all eight statuses, unknown numeric status, mutation, and getter-only behavior.
• Evidence (optional): Local red/green JSON and validation logs retained in the agent session.

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Notes for reviewers

• This PR is independent of durable HTTP work. CANCELED is deliberately excluded to preserve the exact .NET predicate semantics.

[Copilot]

Copilot review overview

🟢 Approval recommended

The implementation matches the documented .NET semantics and has comprehensive focused tests.

Review effort: Balanced
Findings: None

What changed in this PR

Adds .NET-aligned runtime-status predicates to OrchestrationState.

Changes:

• Adds getter-only isRunning and isCompleted properties.
• Tests all statuses, mutation behavior, and getter-only semantics.
• Documents the public API addition.

File	Description
packages/​durabletask-js/​src/​orchestration/​orchestration-state.ts	Implements status predicates.
packages/​durabletask-js/​test/​orchestration-state.spec.ts	Adds predicate regression tests.
CHANGELOG.md	Records the new API.

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