Junaed/fssdk 12294 sync hook impl

[junaed-optimizely]

Summary

New hooks

• useDecide(flagKey, config?) — Returns a feature flag decision (decision, isLoading, error) for a given flag key. Subscribes to ProviderStateStore via useSyncExternalStore and re-evaluates when client readiness, user context, or forced decisions change.
• useOptimizelyClient() — Returns the Optimizely client instance from the nearest provider. Does not re-render on store state changes.
• useOptimizelyUserContext() — Returns the current OptimizelyUserContext (or null). Re-renders only when the user context reference changes, not on unrelated state changes.

Supporting hooks/utilities

• useOptimizelyContext() — Internal hook that reads React context and throws if used outside .
• useStableArray(arr) — Preserves referential identity for inline arrays (e.g. decideOptions) when elements are shallowly equal, preventing unnecessary re-evaluations.
• createDefaultDecision(flagKey) — Helper that produces a safe default OptimizelyDecision while loading or on error.

ProviderStateStore changes

• Listener notifications are now deferred via qqueueMicrotaskq to avoid the React warning "Cannot update a component while rendering a different component". Multiple synchronous state changes are batched into a single notification.
• Added subscribeForcedDecision(flagKey, callback) — per-flag-key subscription so useDecide can react to forced decision changes without re-evaluating unrelated flags.

Dependency changes

• Added use-sync-external-store (with shim for React <18 compat)
• Removed hoist-non-react-statics

Tests

• Comprehensive test suites for useDecide, useOptimizelyClient, and useOptimizelyUserContext covering loading states, error handling, reactivity, referential stability, subscription cleanup, and forced decision behavior.
• Manually tested in different React Envs

Issues

• FSSDK-12293
• FSSDK-112295

[raju-opti]

looks great. few small things commented

[raju-opti]

lgtm