fix: Improve usage reporting

[jsonbailey]

Note

Medium Risk
Changes the analytics/telemetry event names and payload schemas, which can break downstream dashboards or ingestion if consumers still expect the old keys. Functional AI behavior is otherwise unchanged.

Overview
Standardizes AI SDK usage reporting by renaming the track event keys emitted from LDAIClientImpl for config evaluation and object creation (completion/agent/judge, batch agent configs, createChat, createJudge) to the new $ld:ai:usage:* namespace.

Adds constructor-time tracking of SDK identity via a new $ld:ai:sdk-info event sent under an internal anonymous context, including aiSdkName, aiSdkVersion, and new aiSdkLanguage.

Simplifies per-operation tracking payloads by removing aiSdkName/aiSdkVersion from LDAIConfigTrackerImpl.getTrackData() and its interface, with tests updated accordingly.

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[github-actions]

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Uncompressed size: 124693 bytes

[github-actions]

@launchdarkly/browser size report
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[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 19331 bytes
Compressed size limit: 20000
Uncompressed size: 99578 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 23336 bytes
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Uncompressed size: 81070 bytes

[joker23]

LGTM

[kinyoklion]

This is interesting. I feel like we probably shouldn't use 'user'? I feel like we should probably use something more esoteric. It is also interesting to be using a context, but anonymous should handle most concerns.