Complete library cleanup and documentation overhaul

## Library Code Cleanup (~1,200+ lines removed)
- Remove legacy markdown system (markdown.js, previewer.js)
- Delete unused EditContext code from ui/editor.js (~400 lines)
- Remove version history UI components from form-renderer.js (~180 lines)
- Clean unused CSS styles from insertr.css (~120 lines)
- Update package.json dependencies (remove marked, turndown)

## Documentation Updates
- README.md: Update from markdown to HTML-first approach
- AGENTS.md: Add current architecture guidance and HTML-first principles
- TODO.md: Complete rewrite with realistic roadmap and current status
- demos/README.md: Update for development demo server usage

## System Reality Alignment
- All documentation now reflects current working system
- Removed aspirational features in favor of actual capabilities
- Clear separation between development and production workflows
- Accurate description of style-aware editor with HTML preservation

## Code Cleanup Benefits
- Simplified codebase focused on HTML-first approach
- Removed markdown conversion complexity
- Cleaner build process without unused dependencies
- Better alignment between frontend capabilities and documentation

Ready for Phase 3a server updates with clean foundation.

demos/README.md

@@ -1,40 +1,72 @@
-# Test Sites Collection
+# Demo Sites Collection
 
-This directory contains a collection of real-world websites for testing insertr CMS functionality across different site types, CSS frameworks, and complexity levels.
+This directory contains demo sites for testing and showcasing Insertr CMS functionality across different layouts, CSS frameworks, and content types.
 
-## Directory Structure
+## Available Demo Sites
 
-- **`simple/`** - Simple sites with vanilla CSS and minimal layouts
-- **`framework-based/`** - Sites using CSS frameworks (Bootstrap, Tailwind, etc.)
-- **`complex/`** - Complex layouts with advanced interactions
-- **`templates/`** - Template files for new test sites
-- **`scripts/`** - Automation utilities for downloading and enhancing sites
-- **`results/`** - Testing results, reports, and documentation
+### **`default/`** - Basic Demo Site
+- Simple HTML with explicit `class="insertr"` markings
+- Demonstrates basic text and link editing
+- Vanilla CSS styling
 
-## Site Categories
+### **`simple/`** - Minimal Example  
+- Single page with minimal styling
+- Shows container expansion (`.insertr` on parent elements)
+- Good starting point for new implementations
 
-### Simple Sites
-- **dan-eden-portfolio** - Clean personal portfolio with minimal styling
-- **github-pages-simple** - Basic GitHub Pages site with standard layout
+### **`dan-eden-portfolio/`** - Real-World Portfolio
+- Clean personal portfolio with modern styling
+- Uses automatic element discovery (no manual `.insertr` classes)
+- Demonstrates style-aware editing with complex CSS
 
-### Framework-Based Sites
-- **bootstrap-docs** - Bootstrap documentation sections
-- **tailwind-landing** - Tailwind CSS marketing pages
+### **`devigo-web/`** - Multi-Page Site
+- Multiple HTML files with navigation
+- Various content types (headings, paragraphs, buttons, links)
+- Tests cross-page content management
 
-### Complex Sites
-- **stripe-product** - Enterprise product pages with rich content
-- **linear-features** - Modern SaaS feature pages
+## Demo Server Usage
 
-## Testing Process
+### **Development Testing**
+```bash
+# Start demo server with all sites
+just dev
 
-1. **Download** - Use scripts to fetch HTML and assets
-2. **Enhance** - Add insertr classes to content sections
-3. **Test** - Verify functionality across different layouts
-4. **Document** - Record results and compatibility notes
+# Access sites at:
+# http://localhost:8080/sites/default/
+# http://localhost:8080/sites/simple/  
+# http://localhost:8080/sites/dan-eden-portfolio/
+# http://localhost:8080/sites/devigo-web/
+```
 
-## Each Site Includes
+### **Configuration**
+Each demo site is configured in `insertr.yaml`:
+```yaml
+server:
+  sites:
+    - site_id: "default"
+      source_path: "./demos/default"
+      path: "./demos/default_enhanced"
+      auto_enhance: true
+      discovery:
+        enabled: false    # Uses explicit .insertr markings
+        
+    - site_id: "dan-eden-portfolio"  
+      source_path: "./demos/dan-eden-portfolio"
+      path: "./demos/dan-eden-portfolio_enhanced"
+      auto_enhance: true
+      discovery:
+        enabled: true     # Auto-discovers editable elements
+```
 
-- Original HTML files
-- `assets/` directory with CSS, JS, and images
-- `README.md` with site-specific testing notes
-- `insertr-config.json` with enhancement configuration
+### **Testing Features**
+- **Style-Aware Editing**: Each site tests different CSS frameworks and styling approaches
+- **Element Discovery**: Compare manual `.insertr` vs automatic discovery modes
+- **Content Types**: Test text, rich content, links, and multi-property elements
+- **Authentication**: Mock authentication for easy testing without setup
+
+## Adding New Demo Sites
+
+1. Create new directory in `demos/`
+2. Add HTML files and assets
+3. Configure in `insertr.yaml` under `server.sites`
+4. Run `just dev` to test