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 entry ("introduced": "8.12") to .sdk_metadata.json. Version 8.12 added the data_system_config option for FDv2 support.

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

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Note

Low Risk
Documentation/metadata update only; no application logic or security-sensitive paths change.

Overview
Registers FDv2 in .sdk_metadata.json for the Ruby Server SDK with "introduced": "8.12", aligning sdk-meta with the release that added data_system_config for Flag Delivery v2.

This is a metadata-only change; no runtime or API code is modified.

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[devin-ai-integration]

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[kinyoklion]

It seems there may have been a public typing issue that resulted in it really being 8.12.3, but I think this is likely fine.