feat: Add @featureboard/openfeature-node-provider package

[IDurward]

Summary

This PR implements @featureboard/openfeature-node-provider\ - an OpenFeature Provider that wraps @featureboard/node-sdk\ to enable FeatureBoard feature flags with the OpenFeature standard.

What's Included

New Package: libs/openfeature-node-provider/

• Full Provider Implementation: Implements all OpenFeature Provider methods
• Flexible Audience Mapping: 4-layer priority system (custom mapper, explicit array, property map, defaults)
• All Update Strategies: Supports \manual, \polling, and \on-request\
• JSON String Parsing: Automatically parses JSON strings for object-type flags

Test Coverage

• 57 tests passing, 1 skipped
• Tests use MSW to mock FeatureBoard API responses

Key Design Decisions

1. No Features Interface Export: OpenFeature is vendor-agnostic - uses string keys
2. Peer Dependency: @openfeature/server-sdk\ is a peer dependency
3. JSON Parsing for Objects: Auto-parses JSON strings for object types

Usage

import { OpenFeature } from '@openfeature/server-sdk'
import { FeatureBoardProvider } from '@featureboard/openfeature-node-provider'

const provider = new FeatureBoardProvider({
    environmentApiKey: 'your-api-key',
})

await OpenFeature.setProviderAndWait(provider)
const client = OpenFeature.getClient()

const value = await client.getBooleanValue('my-feature', false, {
    audiences: ['premium', 'org:acme'],
})

Checklist

• Package structure created
• All source files implemented
• Tests passing (57 passed, 1 skipped)
• TypeScript compiles cleanly
• README documentation
• Changeset created for versioning