docs: update architecture diagram scratchpad (2026-04-13) (#26000)

Author: github-actions[bot]

scratchpad/architecture.md

@@ -1,6 +1,6 @@
 # Architecture Diagram
 
-> Last updated: 2026-04-10 · Source: [Issue #aw_arch002](https://github.com/github/gh-aw/issues)
+> Last updated: 2026-04-13 · Source: [Issue #24846](https://github.com/github/gh-aw/issues/24846)
 
 ## Overview