feat!: release @launchdarkly/node-client-sdk@4.0.0

[joker23]

This release ports launchdarkly-node-client-sdk onto js-core. The package
moves to @launchdarkly/node-client-sdk and rebases on
@launchdarkly/js-client-sdk-common, picking up the shared client-side
foundation used by the browser and combined-browser SDKs. Consumers
should follow the migration guide for the new initialization flow,
extension surfaces (hooks, inspectors, plugins), and the on-disk cache
format change. See https://launchdarkly.com/docs/sdk/client-side/node-js
for full SDK documentation.

BREAKING-CHANGE: The package name changed from launchdarkly-node-client-sdk to @launchdarkly/node-client-sdk.
BREAKING-CHANGE: Initialization is now done with createClient and start (see docs).
BREAKING-CHANGE: Minimum Node version is now >=18.
BREAKING-CHANGE: The on-disk persistent cache format changed; v3 cache data will not be read by v4 and the anonymous key will be regenerated on first identify.

feat!: identify() resolves an identify result and no longer throws
feat: Evaluation, identify, and track hooks
feat: Inspector support for flag and context state
feat: Plugin extension surface with applicationInfo metadata
feat: Runtime connection-mode control via setConnectionMode
feat: Storage configuration with file-backed default and custom-implementation override
feat: TLS configuration via tlsParams
feat: support client side secure mode with client side id
feat: support wrapper header
feat: Add useMobileKey option to NodeOptions

---

Note

Low Risk
Documentation and release tooling only; no runtime SDK code changes in this diff.

Overview
Prepares @launchdarkly/node-client-sdk for a 4.0.0 GA release by updating release automation and package docs.

release-please-config.json stops treating packages/sdk/node-client as a prerelease (bump-minor-pre-major / prerelease) and pins the next release with release-as: 4.0.0.

The node-client README drops the pre-release CAUTION block that warned about API instability and pinning to minor versions.

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[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 26360 bytes
Compressed size limit: 29000
Uncompressed size: 129188 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 32077 bytes
Compressed size limit: 34000
Uncompressed size: 114525 bytes

[github-actions]

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 179691 bytes
Compressed size limit: 200000
Uncompressed size: 831704 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 39108 bytes
Compressed size limit: 39300
Uncompressed size: 213642 bytes

[joker23]

@cursor review

[cursor]

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[devin-ai-integration]

✅ Devin Review: No Issues Found

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