fix: harden mariadb startup and shared networking

docker-compose.yml

@@ -45,6 +45,9 @@ services:
       - Email__FromName=${EMAIL_FROM_NAME}
     expose:
       - "8080"
+    networks:
+      - default
+      - shared_services
     restart: unless-stopped
 
   frontend:
@@ -58,6 +61,9 @@ services:
       - "3000:80"
     depends_on:
       - backend
+    networks:
+      - default
+      - shared_services
     restart: unless-stopped
 
   summarizer:
@@ -66,6 +72,9 @@ services:
       dockerfile: Dockerfile
     ports:
       - "8001:8001"
+    networks:
+      - default
+      - shared_services
     restart: unless-stopped
     healthcheck:
       test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://127.0.0.1:8001/health', timeout=5).read()"]
@@ -75,3 +84,8 @@ services:
 
 volumes:
   jobtracker_data:
+
+networks:
+  shared_services:
+    external: true
+    name: jobtracker_shared