Docsite Cleanup + Restructure

[captjt]

• Cleaned up the VHS GIFs into asciinema player casts.
• Restructured the pages into a more concise structure without references included in the usages/* pages as well as flattening the React + Typescript tutorial.

Final Structure:

Home
Getting Started
  ├── Installation
  ├── Cupcake CLI
  └── Usage
      ├── Claude Code
      ├── Cursor
      ├── OpenCode
      └── Factory AI
Reference
  ├── Harnesses
  │   ├── Overview
  │   ├── Claude Code
  │   ├── Cursor
  │   ├── OpenCode
  │   └── Factory AI
  ├── Policies
  │   ├── Overview
  │   ├── Builtins
  │   └── Custom
  └── Builtin Config
Tutorials
  ├── Claude Code
  ├── Cursor
  ├── OpenCode
  └── React + TypeScript