Add stop.sh (compose down) and disable print_forge (#34)

## Summary
- Closes [#33](#33).
- Add `scripts/stop.sh` → `playbooks/stop-apps.yml` → `docker compose down` for one `--app` + `--env` (no `-v`; checkouts/secrets stay).
- `host_apps.enabled: false` skips deploy (including CI `--app`) so a stopped app cannot come back. Rows stay for ports and `stop.sh`.
- Disable `print_forge` beta + prod on all app hosts. After merge (or from this branch): `./scripts/stop.sh --app print_forge --env prod` and `--env beta`.

## Test plan
- [ ] `./scripts/stop.sh --help` shows required `--app` / `--env`
- [ ] `ansible-playbook playbooks/stop-apps.yml --syntax-check -e app=print_forge -e app_env=prod`
- [ ] `./scripts/stop.sh --app print_forge --env prod` compose-downs `print_forge_prod` on all webservers
- [ ] `./scripts/stop.sh --app print_forge --env beta` compose-downs `print_forge_beta` (including adama worker)
- [ ] `./scripts/deploy.sh --app print_forge --env prod --check` skips disabled rows (does not start containers)
- [ ] NPM: `print-forge-preview.aimloperations.com` will 502 until the proxy host is disabled (out of scope)

Reviewed-on: #34

README.md

@@ -33,6 +33,10 @@ ansible adama -m ping
 
 # Provision all hosts
 ./scripts/provision.sh
+
+# Stop a compose app (does not remove volumes/checkouts)
+./scripts/stop.sh --app print_forge --env prod
+./scripts/stop.sh --app print_forge --env beta
 ```
 
 See [IMPLEMENTATION.md](IMPLEMENTATION.md) for full architecture, CI/CD plan, and phase breakdown.