feat: update K8s manifests to use regcred secret

Updated all Kubernetes manifests to use 'regcred' secret for image pulling operations instead of 'gitea-registry-secret'.

Changes:
- backend-deployment.yaml: Updated imagePullSecrets to use regcred
- frontend-deployment.yaml: Updated imagePullSecrets to use regcred
- image-pull-secret.yaml: Updated secret name to regcred
- DEPLOYMENT_GUIDE.md: Updated documentation references

All manifests now consistently use the existing 'regcred' secret that's already created in the adopt-a-street namespace for pulling images from the container registry.

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Co-Authored-By: AI Assistant <noreply@ai-assistant.com>

deploy/k8s/DEPLOYMENT_GUIDE.md

@@ -41,7 +41,7 @@ This guide covers the configuration changes needed to deploy Adopt-a-Street with
 ### 1. Create Image Pull Secret
 ```bash
 # Replace YOUR_GITEA_PASSWORD with your actual Gitea password
-kubectl create secret docker-registry gitea-registry-secret \
+kubectl create secret docker-registry regcred \
   --docker-server=gitea-http.taildb3494.ts.net \
   --docker-username=will \
   --docker-password=YOUR_GITEA_PASSWORD \
@@ -131,7 +131,7 @@ kubectl logs -n adopt-a-street deployment/adopt-a-street-frontend
 ### Image Pull Issues
 ```bash
 # Verify image pull secret
-kubectl get secret gitea-registry-secret -n adopt-a-street -o yaml
+kubectl get secret regcred -n adopt-a-street -o yaml
 
 # Test image pull
 kubectl run test-pod --image=gitea-http.taildb3494.ts.net:will/adopt-a-street/backend:latest --dry-run=client -o yaml

deploy/k8s/backend-deployment.yaml

@@ -42,7 +42,7 @@ spec:
                     values:
                       - arm64  # Pi 5 architecture
       imagePullSecrets:
-        - name: gitea-registry-secret
+        - name: regcred
       containers:
         - name: backend
           # Update with your registry and tag

deploy/k8s/frontend-deployment.yaml

@@ -32,7 +32,7 @@ spec:
     spec:
       # Frontend can run on any node (lightweight static serving)
       imagePullSecrets:
-        - name: gitea-registry-secret
+        - name: regcred
       containers:
         - name: frontend
           # Update with your registry and tag

deploy/k8s/image-pull-secret.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 kind: Secret
 metadata:
-  name: gitea-registry-secret
+  name: regcred
   namespace: adopt-a-street
 type: kubernetes.io/dockerconfigjson
 data:
@@ -13,7 +13,7 @@ data:
 # 2. Update the base64 encoded .dockerconfigjson with your credentials
 # 3. Apply with: kubectl apply -f image-pull-secret.yaml
 # 4. To generate the proper config, run:
-#    kubectl create secret docker-registry gitea-registry-secret \
+#    kubectl create secret docker-registry regcred \
 #      --docker-server=gitea-http.taildb3494.ts.net \
 #      --docker-username=will \
 #      --docker-password=YOUR_GITEA_PASSWORD \