feat: Evaluate Monaco worker initialization using the new editor.worker.start API #497

Description

Try the new Monaco worker initialization documented by @volar/monaco following the resolution of volarjs/volar.js#321, which has now been closed.

The upstream commit replaces the previous editor.worker / initialize() approach with editor.worker.start / start(), and documents the required TypeScript module declarations.

Our Text Editor currently uses initialize() from monaco-editor/editor/editor.worker.js, introduced in #460.

Motivation

Evaluate whether the new upstream-documented initialization approach is compatible with our Monaco/Language Service integration and whether we should adopt it.

The change should also be validated in the Vanilla Example.

Proposed Implementation

• Experiment with the editor.worker.start / start() initialization pattern documented by Volar, including the worker message handling.
• Update the local TypeScript module declaration accordingly.
• Verify that Language Service features, including completions, diagnostics and CodeLens, continue working.
• Test the integration in the Text Editor Storybook and in examples/vanilla-web-component, using either:
  • the Text Editor PoC from #380 / PR #488, or
  • the final Dual Editor integration from #369, if already available.
• Document the results and determine whether to adopt the new initialization approach.

Note: the worker console errors tracked in #493 is a separate issue.

Definition of Done

• Implementation: Fully implemented according to the Open Workflow spec.
• Unit Tests: Comprehensive unit tests are included and passing.
• Integration Tests: Verified within the monorepo and target environments (Web/VS Code).
• Documentation: Updated README.md, ADRs, or official docs.
• Performance: No significant regression in editor responsiveness.
• Accessibility: UI changes comply with accessibility standards.