Refactor Canvas interactions to RMA & Support Return Value Transfers

This is an exploration quest to refactor the manual worker messaging in the OffscreenCanvas implementation to use RemoteMethodAccess (RMA), and to enhance RMA to support transferring return values.

Objectives

1. Refactor Neo.worker.Canvas interactions:

   • Convert retrieveCanvas and registerCanvas in src/worker/Canvas.mjs to be exposed via the remote config.
   • Update src/component/Canvas.mjs to call these methods directly via the proxy (e.g., Neo.worker.Canvas.retrieveCanvas(...)) instead of using promiseMessage.

2. Enhance Neo.worker.mixin.RemoteMethodAccess:

   • Challenge: Currently, the resolve method in RMA does not support defining a transfer array for the return value. This prevents Neo.main.DomAccess.getOffscreenCanvas from being converted to RMA, as it needs to transfer the OffscreenCanvas back to the caller.
   • Goal: Modify src/worker/mixin/RemoteMethodAccess.mjs (specifically the resolve and onRemoteMethod logic) to detect if a return value includes transferables (e.g., via a specific return structure like { data: result, transfer: [...] }) and handle the message posting with the transfer list accordingly.

Benefits

• Reduces boilerplate code in components (no more manual promiseMessage construction).
• Provides a cleaner, more method-oriented API for cross-worker operations.
• Unlocks RMA usage for all future methods that need to return transferables (e.g., ImageBitmap, ArrayBuffer).

Context

Discussion originated from the refactoring of OffscreenCanvas support for shared workers (#8118).