feat: externalize appsettings to K8s Secret — config persists independently of image rebuilds

- Add cms-config.yaml (K8s Secret) for staging and production
- Mount appsettings.{Environment}.json from Secret into /app/
- Update CI/CD pipelines to apply Secret before Deployment
- Remove redundant env vars (Kestrel, FileStorage) — now in config file

k8s/production/cms-config.yaml

@@ -0,0 +1,54 @@
+---
+# CMS Application Configuration Secret (Production)
+# This Secret stores appsettings.Production.json externally in K8s
+# so configuration persists independently of Docker image rebuilds.
+#
+# To edit config without redeploying:
+#   kubectl edit secret cms-appsettings
+#   kubectl rollout restart deployment/cms
+#
+apiVersion: v1
+kind: Secret
+metadata:
+  name: cms-appsettings
+  namespace: default
+  labels:
+    app: cms
+    environment: production
+type: Opaque
+stringData:
+  appsettings.Production.json: |
+    {
+      "ZarinPal": {
+        "MerchantId": "4225d555-5fa9-4df0-9b61-1ce152cbbba8",
+        "UseSandbox": false
+      },
+      "CmsBaseUrl": "https://cms.kbs1.ir",
+      "FrontOfficeBaseUrl": "https://kbs1.ir",
+      "ConnectionStrings": {
+        "DefaultConnection": "Server=mssql-svc;Database=KBS;User Id=sa;Password=YourStrong@Passw0rd;TrustServerCertificate=True;"
+      },
+      "SeedWorkers": {
+        "MagicWalletCycleSeed": {
+          "Enabled": true
+        }
+      },
+      "FileStorage": {
+        "UploadPath": "/app/Uploads"
+      },
+      "Kestrel": {
+        "EndpointDefaults": {
+          "Protocols": "Http2"
+        }
+      },
+      "Seq": {
+        "ServerUrl": "http://seq-svc:5341",
+        "ApiKey": "oxpvpUzU1pZxMS4s3Fqq"
+      },
+      "Logging": {
+        "LogLevel": {
+          "Default": "Warning",
+          "Microsoft.AspNetCore": "Warning"
+        }
+      }
+    }