chore: Add manual openLLMetry example

[jsonbailey]

Note

Low Risk
Low risk: adds a new standalone example workspace and documentation without changing any production SDK/runtime logic. Primary risk is dependency/version friction or heavier install size for example consumers.

Overview
Adds a new openai-observability example workspace demonstrating provider-specific observability when calling OpenAI directly (without createChat) by wiring the Node SDK Observability plugin plus OpenTelemetry/OpenLLMetry instrumentation, fetching an AI completion config via completionConfig(), and reporting metrics via tracker.trackMetricsOf(OpenAIProvider.getAIMetricsFromResponse, ...).

Updates the root package.json workspaces to include the new example, and includes its README, .env.example, TypeScript build config, and dependencies needed to run it.

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[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 25566 bytes
Compressed size limit: 26000
Uncompressed size: 125383 bytes

[github-actions]

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 171792 bytes
Compressed size limit: 200000
Uncompressed size: 799857 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 20031 bytes
Compressed size limit: 24000
Uncompressed size: 104850 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 23889 bytes
Compressed size limit: 25000
Uncompressed size: 82740 bytes

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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