feat: Scaffold the text-editor workspace package #223

Description

Editor decided (#208): Monaco.
Language service spike: #209

Create packages/text-editor (@openworkflowspec/text-editor) to host the Monaco-based Open Workflow text surface - the editable content / onChange contract (#224), inline validation markers, and the Monaco binding for the language service.

Use the previously created editor packages as a blueprint

@openworkflowspec/text-editor
├─ monaco-editor
├─ @volar/monaco
└─ @openworkflowspec/language-service

Motivation

Need a new package which follows repo patterns to start implementation

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.