Update documentation to reflect current project structure

- Rename CLAUDE.MD to CLAUDE.md for correct case-sensitive formatting
- Update file structure diagrams across all documentation files
- Document standard Astro src/ directory structure (layouts, pages)
- Add 404.astro custom error page to documentation
- Include robots.txt and sitemap integration in docs
- Update current status to reflect completed features:
  - Custom 404 page with themed styling
  - Sitemap integration for SEO
  - Accessibility improvements (ARIA labels, semantic HTML)
- Update code examples to use proper import paths from src/
- Mark completed TODO items (404 page, sitemap, accessibility)

All documentation now accurately reflects the standard Astro project
structure with layouts in src/layouts/ and pages in src/pages/.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

DEVELOPMENT.md

@@ -19,11 +19,13 @@ cozy-den/
 │   ├── layouts/
 │   │   └── BaseLayout.astro      # Base HTML layout with global styles
 │   ├── pages/
-│   │   └── index.astro            # Main landing page
+│   │   ├── index.astro            # Main landing page
+│   │   └── 404.astro              # Custom 404 error page
 │   └── components/                # (Empty - ready for future components)
 ├── public/
-│   └── favicon.svg                # Site favicon (coffee emoji)
-├── astro.config.mjs               # Astro configuration
+│   ├── favicon.svg                # Site favicon (coffee emoji)
+│   └── robots.txt                 # Search engine directives
+├── astro.config.mjs               # Astro configuration with sitemap
 ├── package.json                   # Node dependencies
 ├── tsconfig.json                  # TypeScript configuration
 ├── Dockerfile                     # Multi-stage Docker build
@@ -67,6 +69,14 @@ The main page includes these sections:
 5. **Support** - Ways to help/contribute
 6. **Footer** - Links and credits
 
+### 404.astro
+
+Custom error page with:
+- Themed styling matching the cozy aesthetic
+- Clear error message ("Lost in the Den?")
+- Action buttons to return home or visit Gitea
+- Responsive design for all devices
+
 ## Development Workflow
 
 ### Local Development