[peter-jerry-ye]

Exported resource methods and destructors receive resource representations, but the MoonBit bindings currently wrap those values as handles. Calling rep() on them can trap or resolve the wrong resource.

This change keeps the original resource name, such as Counter, for the application-defined object and generates an opaque CounterHandle for owned exported resources. A single generated slot array translates incoming representations to objects without a hash table. Vacant slots link to the next free slot, with one free-head reference instead of a separate free-index array. Constructors return objects, including Result[Counter, E] for fallible constructors; adapters register successful results. Handle methods forward to the object implementation, including async methods.

Ownership transfer invalidates the handle wrapper and its aliases. Destruction releases the storage slot before application cleanup, allowing cleanup to allocate or destroy other resources safely. Imported resources keep their existing type and method names, with opaque representations and generated conversion helpers for use across packages.

This is a breaking change to generated MoonBit source interfaces; the WIT interface and component ABI are unchanged. The migration guide explains constructors, ownership, visibility, and cleanup. It distinguishes method computation, explicit background children, and returned endpoint producers: each needs ownership through its own lifetime. The body example labels its collection-before-destruction requirement and explains the additional abandonment policy a production API needs.

Existing resource fixtures retain ordinary call and transfer coverage. The borrowed-record fixture gains a MoonBit implementation; the payload fixture covers nested ownership, async forwarding, collection errors, and cancellation, with a Rust cancellation control. The focused exported-resource-lifecycle fixture covers fallible construction, alias invalidation, reentrant slot reuse, reuse of multiple vacant slots around live resources, background ownership with explicit completion, and started versus unstarted producer cleanup. Its gated background case calls a generated async handle method: a separate borrowed receiver returns while an owned argument stays alive through work in the supplied group. A MoonBit-specific code-generation fixture covers generated-name collisions across interfaces, including new, dtor, and drop, without exposing those adversarial names to other language generators. The generator unit test uses the same WIT fixture. The lifecycle runner is MoonBit, so other language jobs do not select it without its implementation.

Production changes remain confined to the MoonBit generator. The existing CI configuration and other language harnesses are unchanged. Broader async API and runtime collection redesigns are deferred.

Fixes #1724.