Map environment name from environment document

[emyller]

Evaluation context incorrectly maps api_key to environment.name instead of using the name field from the environment document.

Acceptance criteria

• Map environment.name from environment document name field in evaluation context
• Update tests to verify correct environment name mapping

Current behavior

flagsmith-rust-flag-engine/src/engine_eval/mappers.rs

Line 23 in 698c628

key: environment.api_key.clone(),

Note

This fix will make the Rust SDK behavior consistent with other SDKs.