feat: add identity_feature_state to project features endpoint

[SahilJat]

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Changes

Closes #7095

This PR optimizes how identity overrides are fetched on the Identity Page by eliminating chained API calls.

Backend:

• Updated FeatureViewSet.get_queryset in api/features/views.py to accept an identity query parameter. When provided (and the project is not Edge/DynamoDB-enabled), it fetches the resolved identity feature states using identity.get_all_feature_states() and stores them on the view instance.
• Updated FeatureViewSet.get_serializer_context to inject identity_feature_states into the serializer context.
• Updated CreateFeatureSerializer in api/features/serializers.py to include a new identity_feature_state field via SerializerMethodField, which reads from the injected context.

Frontend:

• Added identity_feature_state to the ProjectFlag type in frontend/common/types/responses.ts.
• Added identityStates to the featureList response type in Res.
• Updated getFeatureList in frontend/common/services/useProjectFlag.ts to pass the identity parameter to the API and extract identityStates from the transformResponse.
• Refactored frontend/web/components/pages/IdentityPage.tsx to remove the chained getActualFlags() call (which previously hit /environments/.../identities/.../all/), the actualFlags state, and associated dead Redux code. The component now reads identity_feature_state directly from useGetFeatureListQuery.

How did you test this code?

Automated tests:

• Added integration tests in api/tests/integration/features/test_identity_feature_states.py covering:

  • Identity with an override returns correct identity_feature_state (enabled + value)
  • No identity param → identity_feature_state is None (backward compatibility)
  • Invalid/non-existent identity ID → identity_feature_state is None (graceful handling)
  • Edge (DynamoDB) project → identity_feature_state is None (no Postgres crash)
  • Identity from a different environment → identity_feature_state is None
  • Identity exists but has no override → identity_feature_state is None

• Added unit tests in api/tests/unit/features/test_unit_identity_feature_states.py covering:

  • Serializer returns identity state from context when present
  • Serializer returns None when context has empty identity states
  • Serializer returns None when identity_feature_states key is missing from context

Manual testing steps:

1. Start the Flagsmith backend and frontend locally.
2. Navigate to a project → environment → Identities page.
3. Open an identity that has at least one feature override.
4. Verify the feature list loads correctly and overrides are displayed.
5. Open the browser network tab — confirm only one call is made to /projects/{id}/features/?environment=X&identity=Y and the old /identities/.../all/ call is gone.
6. Verify features without identity overrides show environment defaults correctly.

[claude]

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