Add missing cancel option to 15 more multi-instance services; add setup.sh --status

Same bug as the previous filebrowser/fmd fix: vaultwarden, immich,
audiobookshelf, homebox, rustdesk, emby, meshcentral, traccar, lyrion,
actualbudget, mealie, joplin, jellyfin, unifi, and ntfy all showed "Manage
that install (update / full reinstall / cancel)" when re-run against an
existing install, but choosing "1) Manage" fell straight through into the
same unconditional fresh-install flow every time regardless of choice —
no way to actually cancel or update in place. Wired all 15 up to
prompt_reinstall_mode, matching the reference pattern in
services/mattermost.sh: update pulls + restarts the existing container
without touching config, cancel leaves the install untouched, fresh falls
through to the existing full-install flow unchanged.

Also add `setup.sh --status`: a plain-text listing of every service with
its install state, using the exact same is_installed() calls the whiptail
checklist's [installed] marker uses. Exists so "is X actually installed"
can be answered by reading terminal output directly, without depending on
a whiptail checklist screen where a narrow/resized terminal can truncate
the "[installed]" suffix off-screen with no visible sign that happened.

services/jellyfin.sh

@@ -257,6 +257,28 @@ install_jellyfin() {
             log_warning "DLNA/discovery (1900/udp, 7359/udp) are fixed, host-wide ports already"
             log_warning "claimed by the first instance — this instance skips them (web UI and"
             log_warning "app-based streaming are unaffected; DLNA auto-discovery is not)."
+        else
+            # "Manage that install" on THIS instance — the banner above promises
+            # update/fresh/cancel, so actually offer it instead of falling straight
+            # through into the same unconditional-overwrite flow as a new install.
+            if [[ -f "$JELLYFIN_DIR/docker-compose.yml" ]]; then
+                local MODE=""
+                prompt_reinstall_mode MODE
+                case "$MODE" in
+                    update)
+                        log_info "Refreshing the Jellyfin image only — existing config, port, and Caddy setup are left as-is."
+                        ( cd "$JELLYFIN_DIR" && docker compose pull && docker compose up -d ) \
+                            && log_success "Jellyfin image refreshed" \
+                            || log_warning "Refresh failed — check: docker compose -f $JELLYFIN_DIR/docker-compose.yml logs"
+                        return 0
+                        ;;
+                    cancel)
+                        log_info "Leaving the existing install as-is."
+                        return 0
+                        ;;
+                    fresh) ;;  # fall through to the full install flow below
+                esac
+            fi
         fi
     fi