Add screenshots to marketing example READMEs

Insert thumbnail galleries linking to full-size images hosted on
GitHub Pages for budget-allocator, cohort-heatmap, customer-segmentation,
scenario-modeler, and system-monitor server examples.

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

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

examples/customer-segmentation-server/README.md

@@ -2,6 +2,14 @@
 
 A demo MCP App that displays customer data as an interactive scatter/bubble chart with segment-based clustering. Users can explore different metrics, filter by segment, and click to see detailed customer information.
 
+<table>
+  <tr>
+    <td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/customer-segmentation-server/01-account-age-revenue.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/customer-segmentation-server/01-account-age-revenue.png" alt="Account age vs revenue" width="100%"></a></td>
+    <td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/customer-segmentation-server/02-tickets-nps-engagement.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/customer-segmentation-server/02-tickets-nps-engagement.png" alt="Tickets, NPS, engagement" width="100%"></a></td>
+    <td><a href="https://modelcontextprotocol.github.io/ext-apps/screenshots/customer-segmentation-server/07-age-engagement-revenue.png"><img src="https://modelcontextprotocol.github.io/ext-apps/screenshots/customer-segmentation-server/07-age-engagement-revenue.png" alt="Age, engagement, revenue" width="100%"></a></td>
+  </tr>
+</table>
+
 ## Features
 
 - **Interactive Scatter Plot**: Bubble chart visualization using Chart.js with configurable X/Y axes