fix: $group_key should be override in local eval

[orian]

Fixes missing $group_key override

fixes: #98

[Copilot]

Pull Request Overview

This PR ensures that the $group_key is correctly injected into group-based feature‐flag evaluations by cloning the original properties and avoiding side effects. It also renames several “Decide” methods to “Remote” and updates tests and fixtures to cover the new behavior.

• Added a Clone method on Properties to safely duplicate maps.
• Swapped getFeatureFlag*FromDecide calls for *FromRemote in posthog.go.
• Injected $group_key into the cloned group properties in computeFlagLocally and added corresponding tests/fixtures.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
properties.go	Added Clone() for Properties and adjusted the doc comment.
posthog.go	Renamed “Decide” methods to “Remote” and updated interface comments.
groups.go	Fixed the type comment for Groups.
groups_test.go	Switched to table-driven tests using testify/require.
fixtures/feature_flag/*.json	Added JSON fixtures for group props and false-variant scenarios.
featureflags.go	Cloned and injected $group_key into group properties during local evaluation.
feature_flags_local_test.go	Expanded local-eval tests (note: missing imports).

Comments suppressed due to low confidence (2)

groups.go:4

• Grammar issue: change "a free-form objects" to "a free-form object" (singular) to match the type.

// a free-form objects so the application can set any value it sees fit but

feature_flags_local_test.go:94

• The test uses require assertions but the testify/require package is not imported. Add "github.com/stretchr/testify/require" (and other needed imports like net/http/httptest and strings) to the import block.

require.Error(t, err)

[haacked]