Add CI workflow for Docker build and deployment; update Dockerfile and adjust health reduction logic in PetActionService; modify database connection string in appsettings.json

appsettings.json

@@ -7,6 +7,6 @@
   },
   "AllowedHosts": "*",
   "ConnectionStrings": {
-    "DefaultConnection": "Data Source=petcompanion.db"
+    "DefaultConnection": "Data Source=game-data/petcompanion.db"
   }
 }