release blocker: object-literal shape path overwrites generator lexical this

[proggeramlug]

Release v0.5.1519 Full CI run 33305504723 failed cargo-test-perry (5/8) on exact commit 7b57bbd70f021bd199cdbd53dcbb91a697967b0d.

Failure:

generator_using_own_char_at_in_switch_loop_terminates
TypeError: charAt is not a function

Job: https://github.com/PerryTS/perry/actions/runs/33305504723/job/99241270651

The failure reproduces deterministically on the dedicated Linux server with:

cargo test -p perry --test issue_6065_class_method_shadows_string_char_access generator_using_own_char_at_in_switch_loop_terminates -- --exact --nocapture

Root cause: #9122 added post-build this patching for captures_this closures on the object-literal shape-cache path. Synthesized generator iterator objects are the { next, return, throw } closure literal recognized by is_generator_iterator_object_literal; their step closures already capture the generator invocation's lexical this. The new generic patch loop overwrites that reserved capture with the iterator object itself. Inside a class generator, this.charAt(0) therefore dispatches against { next, return, throw } and throws.

Acceptance:

• Generator iterator object literals do not overwrite their step closures' lexical this capture.
• Ordinary object-literal methods using dynamic this still receive the completed object on both shape and by-name paths.
• issue_6065_class_method_shadows_string_char_access passes in full.
• Existing object-literal codegen unit tests and formatting pass.
• Release Full CI passes on the resulting exact release commit.