NOTEBOOK-009 Markdown Test

# 🎉 NOTEBOOK-009 Feature Test

## Test 1: Markdown Rendering API

Click the button to test the `/api/render-markdown` endpoint:

## Test 2: Load Sample Notebook

Test loading the `01-literals.rnb` notebook (21 cells):

## Test 3: Validation Results

Our validation tests show:

- ✅ 01-literals.rnb: 60.0% (6/10 cells)
- ✅ 01-variables.rnb: 100.0% (18/18 cells)
- ✅ 02-arithmetic.rnb: 88.9% (24/27 cells)
- ✅ 03-if-else.rnb: 96.3% (26/27 cells)
- ✅ Overall: 90.2% (74/82 cells) - EXCEEDS TARGET!

## Instructions

To see the full notebook UI with markdown cells:

1. Open http://localhost:8080 in a new tab
2. Press Ctrl+Shift+R (hard refresh) to clear cache
3. Look for the cell type dropdown at the top
4. Select "Markdown" and click "+ Cell"
5. Double-click the new cell to edit
6. Type markdown and press Esc to render