Overhaul deployment to Gitea Actions CI/CD, remove update.sh

Production no longer builds from source or self-updates via cron/git pull:
setup.sh now only provisions the server once (Docker, /opt/anouma, a
restricted `anouma-deploy` SSH user whose key can only ever run
deploy.sh, generated secrets). All future deployments run through
.gitea/workflows/ci.yml (lint/typecheck/test/build on every push) and
release.yml (on a vX.Y.Z tag: build the image, push it to the Gitea
registry, then SSH-trigger deploy.sh on the server), which pulls,
migrates, restarts, healthchecks, backs up the database first, and
automatically rolls back the code on a failed healthcheck.

docker-compose.yml's app service now runs a registry image
(${ANOUMA_IMAGE}) instead of building locally.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/(payload)/api/health/route.ts

@@ -7,7 +7,7 @@ export const dynamic = "force-dynamic";
 
 /**
  * Used by the Docker healthcheck (see docker-compose.yml) and by
- * setup.sh/update.sh to confirm the app can actually reach Postgres before
+ * setup.sh/deploy.sh to confirm the app can actually reach Postgres before
  * being considered "up" — not just that the Node process is listening.
  */
 export async function GET() {