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-core/Cargo.toml

@@ -19,5 +19,5 @@ sha2 = { workspace = true }
 hex = { workspace = true }
 uuid = { workspace = true }
 secrecy = { workspace = true }
-bson = "2"
+bson = { version = "2", features = ["chrono-0_4"] }
 mongodb = { workspace = true, optional = true }