Build a ClassBlueprint from ClassExpression elements at codegen time:
- Methods/getters/setters: register SharedFunctionInstanceData from
the method's FunctionExpression
- Field initializers with literal values (numbers, booleans, null,
strings, negated numbers): store the value directly, avoiding
function creation entirely
- Field initializers with non-literal values: wrap in
ClassFieldInitializerStatement and create SharedFunctionInstanceData
- Static initializers: create SharedFunctionInstanceData from the
function body
- Constructor: register SharedFunctionInstanceData from the
constructor's FunctionExpression
Add public accessors to ClassMethod::function() and
StaticInitializer::function_body() for codegen access.
The blueprint is registered but not yet used by NewClass (dual path).
No behavioral change.