feat: Add support for trackStreamMetricsOf method

[jsonbailey]

fix: Deprecated toVercelAISDK, trackVercelAISDKStreamTextMetrics, use @launchdarkly/server-sdk-ai-vercel package

---

Note

Add streaming metrics tracking API and deprecate Vercel mapping APIs/types in favor of @launchdarkly/server-sdk-ai-vercel.

• AI Metrics Tracking:
  • Add trackStreamMetricsOf() to LDAIConfigTracker and implement in LDAIConfigTrackerImpl, with background metrics extraction via _trackStreamMetricsInBackground() for streaming operations (duration, success/error, token usage).
• Deprecations/Migrations:
  • Mark toVercelAISDK() in LDAIConfig and LDAIConfigMapper as deprecated in favor of VercelProvider.toVercelAISDK() from @launchdarkly/server-sdk-ai-vercel.
  • Deprecate trackVercelAISDKStreamTextMetrics() in LDAIConfigTracker in favor of trackStreamMetricsOf() with VercelProvider.createStreamMetricsExtractor().
  • Deprecate VercelAISDKProvider, VercelAISDKMapOptions, and VercelAISDKConfig types, pointing to the @launchdarkly/server-sdk-ai-vercel package.

^{Written by Cursor Bugbot for commit ff14518. This will update automatically on new commits. Configure here.}

[github-actions]

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 169118 bytes
Compressed size limit: 200000
Uncompressed size: 789399 bytes

[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 24988 bytes
Compressed size limit: 26000
Uncompressed size: 122411 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 21721 bytes
Compressed size limit: 25000
Uncompressed size: 74698 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 17636 bytes
Compressed size limit: 20000
Uncompressed size: 90259 bytes