feat: Implement Promise.finally method and refactor Promise module

- Add js_promise.rs module, separating Promise code from core.rs
- Implement Promise.prototype.finally method with callback execution
- Fix parser to allow reserved keywords as property names (support obj.finally() syntax)
- Improve error handling with new JSError::Throw variant
- Unify evaluate_script function, remove evaluate_script_async
- Add Promise.finally test case
- Fix function call references in async tests
- Improve Promise rejection error message formatting

Author: ssrlive

src/core.rs

@@ -24,6 +24,9 @@ pub enum JSError {
     #[error("Runtime error: {message}")]
     RuntimeError { message: String },
 
+    #[error("Thrown value: {value:?}")]
+    Throw { value: crate::core::Value },
+
     #[error("std::io error: {0}")]
     IoError(#[from] std::io::Error),
 }

src/error.rs

@@ -162,7 +162,7 @@ pub(crate) fn evaluate_new(env: &JSObjectDataPtr, constructor: &Expr, args: &[Ex
                     return handle_string_constructor(args, env);
                 }
                 "Promise" => {
-                    return crate::js_function::handle_promise_constructor(args, env);
+                    return crate::js_promise::handle_promise_constructor(args, env);
                 }
                 _ => {
                     log::warn!("evaluate_new - constructor is not an object or closure: Function({func_name})",);