chore: update Docker setup

- Replace lowercase dockerfile with proper Dockerfile
- Add .dockerignore for cleaner builds
- Add build.sh script
- Update docker-compose.yml: separate volumes for config, database, plugins; set restart policy to unless-stopped; remove deprecated version field

docker-compose.yml

@@ -1,11 +1,15 @@
 # Docker Compose for Open Ticket v4
-version: '3'
 services:
   openticket:
     build: .
     volumes:
-      - openticket:/home/container
-    restart: no
+      - config:/home/container/config
+      - database:/home/container/database
+      - plugins:/home/container/plugins
+    restart: unless-stopped
     container_name: open-ticket
+
 volumes:
-  openticket:
+  config:
+  database:
+  plugins: