docs: add dat diagram to deployment guide

Author: Donovan1905

docs/deployment/DAT-Archi-Oct-2025.png

@@ -117,4 +117,10 @@ Use this as a quick checklist to estimate costs. “Mandatory” means required
 Evidence Bookmark: Billable Services List
 - Link: docs/deployment/guide.md
 - Section: Costs > Billable AWS services (Mandatory vs Optional)
-- Paragraph: Table above
+- Paragraph: Table above
+
+## Architecture diagram
+
+Please find below the architecture diagram of the solution.
+
+![Architecture diagram](./DAT-Archi-Oct-2025.png)