chore: Declare the hook-environment-id contract test capability

[kinyoklion]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

Depends on launchdarkly/sdk-test-harness#410, which adds the hook-environment-id capability and a test asserting evaluationSeriesContext.environmentId.

Describe the solution you've provided

The node server contract-test service only needed to declare the capability: TestHook forwards the whole EvaluationSeriesContext to the callback, so environmentId is already in the payload, and HookRunner gets it from getInitMetaData().

Verified with a local build of the harness branch: hooks/evaluation/provides the environment ID passes.

Describe alternatives you've considered

None; no code change is required beyond the capability.

Additional context

The capability only takes effect once the harness change is released; until then it is ignored by the harness.

Link to Devin session: https://app.devin.ai/sessions/bfe54128e2804a96bb100e6120e9a3ef
Requested by: @kinyoklion

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Note

Overview
Registers the hook-environment-id contract-test capability on the Node server contract-test service so the harness can run the evaluation-hook test that checks evaluationSeriesContext.environmentId.

No SDK logic changes in this PR—the service already forwards the full evaluation series context (including environment ID from init metadata) to hook callbacks; this only advertises support to the test harness once the harness change is available.

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