feat: add secure Pi-hole DNS management

compose.yml

@@ -1,12 +1,15 @@
 services:
   dyndns:
-    image: git.j-mahler.de/admin/domain-control-webinterface-prod:v1.1.0
+    image: git.j-mahler.de/admin/domain-control-webinterface-prod:v1.2.0
     restart: unless-stopped
     ports:
       - "9090:8080"
     volumes:
       - dyndns-data:/data
       - dyndns-secrets:/secrets
+    read_only: true
+    tmpfs:
+      - /tmp:rw,noexec,nosuid,nodev,size=16m,mode=1777
     security_opt:
       - no-new-privileges:true
     cap_drop: