Add budget-allocator-server example

Demo MCP App for interactive budget allocation with:
- Slider controls for 5 categories (Marketing, Engineering, etc.)
- Real-time donut chart visualization via Chart.js
- 24-month sparkline trends per category
- Industry benchmark percentile badges
- Company stage selector (Seed through Growth)
- Budget preset buttons ($50K-$500K)

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

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

examples/budget-allocator-server/src/global.css

@@ -0,0 +1,14 @@
+* {
+  box-sizing: border-box;
+}
+
+html, body {
+  font-family: system-ui, -apple-system, sans-serif;
+  font-size: 14px;
+  margin: 0;
+  padding: 0;
+}
+
+code {
+  font-size: 1em;
+}