chore: Update sdk_metadata features

[devin-ai-integration]

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

N/A — metadata-only change.

Describe the solution you've provided

Add fdv2 feature entries to .sdk_metadata.json:

• Browser SDK: "introduced": "4.9" (Data saving mode EAP)
• React Native SDK: "introduced": "10.19" (Data saving mode EAP)
• React Web SDK: "introduced": "4.1.2" (Data saving mode EAP, via Browser SDK dependency)

Describe alternatives you've considered

N/A

Additional context

Part of a batch update across SDK repos to register FDv2 support in sdk-meta.

Link to Devin session: https://app.devin.ai/sessions/38b4be153c46469b8fcfdd9592381463

[devin-ai-integration]

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[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 26365 bytes
Compressed size limit: 29000
Uncompressed size: 129044 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 38739 bytes
Compressed size limit: 39000
Uncompressed size: 212244 bytes

[github-actions]

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 179579 bytes
Compressed size limit: 200000
Uncompressed size: 831422 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 31978 bytes
Compressed size limit: 34000
Uncompressed size: 114243 bytes

[kinyoklion]

This SDK also has support.

[devin-ai-integration]

Good catch — added "fdv2": { "introduced": "4.1.2" } to react-client-sdk. That's the version where FDv2 EAP landed via the Browser SDK dependency.