Tekton Phase 2 Day 3: Complete Harbor authentication and test build

- Added config.json key to harbor-credentials ExternalSecret
  This ensures kaniko can find the Docker auth config at /kaniko/.docker/config.json
  (previously only .dockerconfigjson was present)

- Created test-app-build PipelineRun manifest for validation testing

- Successfully validated end-to-end pipeline:
  ✅ git-clone Task deployed and working
  ✅ kaniko-build Task deployed and working
  ✅ container-build Pipeline deployed and working
  ✅ Harbor authentication working with robot account
  ✅ Test image built and pushed: the-seas.local.mk-labs.cloud/library/test-app:v1.0.0
  ✅ Image digest: sha256:aa143f4a01795a1d307b711108ca0c89f36e00ea38fddb9d7b2febd5fffc46d7

Pipeline test results:
- PipelineRun: test-app-build-005 - SUCCEEDED
- fetch-repository TaskRun - SUCCEEDED
- build-and-push TaskRun - SUCCEEDED

Tekton CI/CD platform is now operational and ready for production workloads.

cluster/tekton/pipelineruns/test-app-build.yaml

@@ -0,0 +1,34 @@
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  name: test-app-build-005
+  namespace: innoventions
+  labels:
+    app: test-app
+    pipeline: container-build
+  annotations:
+    description: "Test build of sample application to validate Harbor authentication"
+spec:
+  pipelineRef:
+    name: container-build
+  timeout: 30m
+  params:
+    - name: git-url
+      value: https://gitea.mk-labs.cloud/rblundon/homelab.git
+    - name: git-revision
+      value: main
+    - name: image-name
+      value: the-seas.local.mk-labs.cloud/library/test-app
+    - name: image-tag
+      value: v1.0.0
+    - name: dockerfile
+      value: ./test-app.Dockerfile
+    - name: context
+      value: ./
+  workspaces:
+    - name: shared-workspace
+      persistentVolumeClaim:
+        claimName: tekton-workspace
+    - name: docker-credentials
+      secret:
+        secretName: harbor-credentials