fix: clippy warnings and CI Node.js deprecation

- Remove unused imports in session.rs, buffer.rs, engine.rs
- Allow dead_code on intentionally unused fields (decoder, received_at)
- Allow enum_variant_names on Message enum
- Add FORCE_JAVASCRIPT_ACTIONS_TO_NODE24 to CI env

.github/workflows/ci.yml

@@ -10,6 +10,7 @@ on:
 
 env:
   CARGO_TERM_COLOR: always
+  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
 
 jobs:
   # Test job