Pin Docker image versions and fix config drift

- Pin all :latest tags to specific versions for reproducibility:
  jellyfin→10.11.6, gitea→1.24, portainer→2.39.0, qbittorrent→5.1.4
- Fix nextcloud config drift: repo had :29, live was running :32
- Fix qbittorrent: remove user: directive (breaks s6-overlay init)
- Fix portainer: remove healthcheck (distroless image has no shell)

config/docker/portainer/docker-compose.yml

@@ -9,7 +9,7 @@
 
 services:
   portainer:
-    image: portainer/portainer-ce:latest
+    image: portainer/portainer-ce:2.39.0
     container_name: portainer
     restart: unless-stopped
 
@@ -38,13 +38,7 @@ services:
           cpus: '0.1'
           memory: 128M
 
-    # Health check
-    healthcheck:
-      test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:9000/api/status"]
-      interval: 30s
-      timeout: 10s
-      retries: 3
-      start_period: 30s
+    # No healthcheck — Portainer is distroless (no shell available)
 
 volumes:
   portainer_data: