feat: add demo infrastructure and documentation

Add comprehensive demo and documentation infrastructure including:
- Demo documentation (eval harness, quickref, summary)
- Build automation with Makefile
- Documentation demos (slides, walkthrough, terminal demo)
- Demo generation scripts (build, slides, recording)
- Mermaid diagram support for documentation
- Test coverage for demo generation
- Updated markdown link checker to ignore Jekyll internal links

This infrastructure supports creating interactive demos and enhanced
documentation experiences for AgentReady users.

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

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: jeremyeder

.markdown-link-check.json

@@ -17,6 +17,15 @@
     },
     {
       "pattern": "^\\{\\{.*\\}\\}$"
+    },
+    {
+      "pattern": "^/agentready/"
+    },
+    {
+      "pattern": "^/demos/"
+    },
+    {
+      "pattern": "^/tbench"
     }
   ],
   "timeout": "20s",