Add Umami to the apps catalog

[everonegraham]

Add Umami as a one-click app in the Apps catalog.

Umami is a lightweight, privacy-focused alternative to Google Analytics that doesn't use cookies or collect personal data, letting you track website traffic and user behavior without annoying cookie banners.

Website: https://umami.is/

Github: https://github.com/umami-software/umami

Docker Compose: https://github.com/umami-software/umami/blob/master/docker-compose.yml

[Hydralerne]

Shipped in 0.6.2 — Umami is in the catalog as of 698893e (merged to main via #536).

Two services (umami on ghcr.io/umami-software/umami:postgresql-v2.19.0, umami-db on postgres:16-alpine), auto-generated POSTGRES_PASSWORD and APP_SECRET, healthchecks on both, and edge routing to the dashboard. First login is admin / umami — change it from Settings → Profile immediately after signing in.

Verified live before closing: both containers reach healthy, /api/heartbeat returns {"ok":true}, Prisma migrations run clean on PG16, and the default credentials authenticate.

Thanks @everonegraham for the request. @Jcorderop02 also opened #534 for this independently — closed as superseded, with the details there.