docs: add demo testing guide for PR reviewers

- Created instructions for reviewers to test the interactive demo
- Provided multiple options: local checkout, raw file viewing, static preview
- Explains why live links won't work until PR is merged
- Helps reviewers experience the full animation during review process

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

Co-Authored-By: Claude <[email protected]>
Signed-off-by: Yossi Ovadia <[email protected]>

Author: yossiovadia

e2e-tests/llm-katan/DEMO_TESTING.md

@@ -0,0 +1,34 @@
+# Testing the Interactive Demo
+
+## For PR Reviewers
+
+Since the live demo links won't work until this PR is merged, here are ways to see the animation:
+
+### Option 1: Quick Local Test
+```bash
+# Check out the PR branch
+git fetch origin pull/240/head:terminal-demo-test
+git checkout terminal-demo-test
+
+# Open the demo in your browser
+open e2e-tests/llm-katan/terminal-demo.html
+# or on Linux: xdg-open e2e-tests/llm-katan/terminal-demo.html
+```
+
+### Option 2: View Raw File
+1. Go to the [terminal-demo.html file in this PR](https://github.com/vllm-project/semantic-router/pull/240/files#diff-terminal-demo.html)
+2. Click "View file"
+3. Copy the content to a local `.html` file
+4. Open in browser
+
+### Option 3: Static Preview
+The README already includes a collapsible preview showing the terminal output - this works immediately in the PR!
+
+## What You'll See
+- 3-panel terminal layout
+- Realistic typing animations
+- Multi-instance setup demonstration
+- Professional terminal styling
+- Complete workflow from install to testing
+
+The demo showcases llm-katan's key feature: running one tiny model as multiple different AI providers for testing.