fix(keep_names): don't emit class static blocks for targets without them - #11497

Fixes #11469

When keepNames needs to restore a class name, the finalizer injects static { __name(this, "Foo") }. That runs after the transform step, so it never gets lowered, and a build with transform.target: 'es2018' ends up with ES2022 syntax in it.

If the target doesn't support class static blocks (ESFeature::ES2022ClassStaticBlock), the helper now goes outside the class body, the same way it already does for functions:

• class declarations: __name(Foo$1, "Foo") goes right after the declaration (using the existing keep_name_statement_to_insert path)
• anonymous class expressions, export default class {} and export default (class {}): /* @__PURE__ */ __name(class {}, "Foo")

Targets that do support static blocks get the same output as before.

For export default class {} I build var default = __name(class {}, "default") directly rather than queueing a statement. The queued position is computed before the walk, and visit_statements inserts its own statements first, so the position would be stale whenever the module also has a renamed class or function declaration earlier on.

Added keep_names/unsupported_class_static_block (target es2018). It covers a renamed declaration, an anonymous class expression, a self-referencing class, a nested class, and the three default-export shapes. Without the fix the snapshot has six static { blocks. With it there are none, and the name asserts still pass when the output runs.