Support `$.flags` context values in segment conditions

Support `$.flags..` conditions.

### Acceptance criteria

- The engine dependency is bumped to the version supporting `$.flags` context values.
- Identity-less evaluation passes segments to the engine so `$.flags` and `$.environment` conditions resolve.

Start by locating the engine dependency declaration and the identity-less evaluation entry point. Trace how segments are passed to the engine, then verify that $.flags and $.environment conditions resolve and that the dependency version supports the required context values.

Written by the indexing model from the issue text.