Restructure the Learn pages

[Mark90]

Goal

• Have a natural flow of information on the Learn page
• Move away reference/implementation docs from current Learn (UI / forms) pages to subproject

Current structure

• Concepts
  • Framework
  • Orchestrator UI
  • Input Forms
• Example Orchestrator Workshop: ...

Proposed structure

• At a Glance: "What is the Workflow Orchestrator?" -> see [Enhancement]: "Not a Video" crash course #19
• The Framework: make this a high-level overview about the components, and key interactions between them (i.e. UI components / forms)
• Getting Started: new page that outlines the minimal steps needed to deploy the Workflow Orchestrator backend, frontend and additional components. (can link to getting started from subprojects)
• Example Orchestrator Workshop: ... (unchanged)

Details

Goal

• Move Orchestrator UI content into Orchestrator UI Library docs (tab already exists).
• Move Input Forms content into Pydantic Forms and/or Orchestrator Core reference docs, split by whether it's package API or backend integration.
• Leave in Framework only the cross-project concept a reader needs — what forms are and why they exist — linking out for detail.
• Reconcile the two existing forms write-ups in Core (reference-docs/forms.md) and UI Library (forms/index.md): pick one canonical location per topic instead of two drifting copies.