Add DAST, graph modules, toast notifications, and dashboard enhancements

Add DAST scanning and code knowledge graph features across the stack:
- compliance-dast and compliance-graph workspace crates
- Agent API handlers and routes for DAST targets/scans and graph builds
- Core models and traits for DAST and graph domains
- Dashboard pages for DAST targets/findings/overview and graph explorer/impact
- Toast notification system with auto-dismiss for async action feedback
- Button click animations and disabled states for better UX

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

compliance-graph/src/graph/mod.rs

@@ -0,0 +1,4 @@
+pub mod community;
+pub mod engine;
+pub mod impact;
+pub mod persistence;