Show the 10 most recent deployments on the deployments page (closes #238)

An app's deployments page listed up to 50 deployments; it now lists the
10 most recent, newest first. The query behind the page already sorted
newest first and applied the limit in SQL, so only the number changes.
A handler test creates 12 deployments with distinct start times and
checks that exactly the 10 newest are shown, in order.

Model: opus-5-5

TODO.md

@@ -20,6 +20,9 @@ regress.
 
 # Completed Steps
 
+- 2026-09-29: An app's deployments page now lists only its 10 most recent
+  deployments, newest first, instead of 50 (#238).
+
 - 2026-09-29: `docker-compose.yml` now sets `UPAAS_PORT` to 8080 as well as
   `PORT`, since upaas reads `UPAAS_PORT` first and a `UPAAS_PORT` in `.env` made
   it listen away from the port mapping and healthcheck; the README's Compose