Worklets: fixed memleak in shareable and serializable

[tshmieldev]

Summary

we did .release() on jsi value without freeing the memory, leaking ~20B per instance
fixed
👽

Test plan

Stuff works, allocation 1_000_000 jsi values in cpp and then releasing them leaks
but after ::operator delete'ing them no leak

[Copilot]

Pull request overview

This PR addresses a small but repeated memory leak when retaining jsi::Value wrappers after their owning JSI runtime has been torn down, by freeing the heap allocation while still intentionally skipping ~jsi::Value to avoid use-after-free crashes.

Changes:

• In Shareable::~Shareable, when the host runtime is gone, free the released jsi::Value wrapper allocation via ::operator delete(...) instead of leaking it.
• In cleanupIfRuntimeExists, when a runtime is no longer alive, free the released jsi::Value wrapper allocation via ::operator delete(...) instead of leaking it.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
packages/react-native-worklets/Common/cpp/worklets/SharedItems/Shareable.cpp	Frees the jsi::Value wrapper allocation when skipping destruction after host runtime teardown.
packages/react-native-worklets/Common/cpp/worklets/SharedItems/Serializable.h	Frees the jsi::Value wrapper allocation in the “runtime dead” cleanup path while still skipping ~jsi::Value.

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