fix: update Mermaid diagrams to include leadAgent -> dbAgent routing

- Add missing leadAgent -.-> dbAgent; edge to test expectation
- Update README.md diagram to match actual graph structure
- Ensures test consistency with implemented workflow routing

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

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

Author: MH4GF

frontend/internal-packages/agent/README.md

@@ -21,6 +21,7 @@ graph TD;
 	__start__ -.-> validateInitialSchema;
 	__start__ -.-> leadAgent;
 	leadAgent -.-> pmAgent;
+	leadAgent -.-> dbAgent;
 	leadAgent -.-> __end__;
 	classDef default fill:#f2f0ff,line-height:1.2;
 	classDef first fill-opacity:0;

frontend/internal-packages/agent/src/createGraph.test.ts

@@ -20,6 +20,7 @@ graph TD;
 	__start__ -.-> validateInitialSchema;
 	__start__ -.-> leadAgent;
 	leadAgent -.-> pmAgent;
+	leadAgent -.-> dbAgent;
 	leadAgent -.-> __end__;
 	classDef default fill:#f2f0ff,line-height:1.2;
 	classDef first fill-opacity:0;