Spike: Decide on approach for language service

[lornakelly]

Description

Evaluate and decide how we deliver schema-driven autocomplete/IntelliSense: reuse an existing library/language server vs build our own. The chosen service must be a standalone, host-agnostic engine as it will be reused beyond milestone 1 (VsCode, IntelliJ etc).

Comment on this ticket with findings and review with team

Motivation

Authoring assistance is crucial to support the two ADR use cases:

1. Make editor approachable for the newcomer
2. Faster for authoring and debugging for the fixer

Proposed Implementation

No response

Definition of Done

• Implementation: Fully implemented according to the Serverless 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.