test: add workflow visibility tests for poimen-harness namespace

Verify that WorkflowAdapter provides visibility into terminated workflows
in the poimen-harness namespace. This ensures namespace pass-down feature
is working correctly and users can specify different domains/namespaces
via X-Service: workflow requests.

Tests added:
1. integration-test.sh: Added workflow visibility tests
   - List workflows in poimen-harness namespace
   - Verify terminated/completed workflows are visible
   - Validate namespace parameter requirement
   - Check auth enforcement

2. workflow-visibility-test.sh: NEW dedicated workflow test script
   - Tests WorkflowAdapter namespace pass-down
   - Verifies list, describe, and auth enforcement
   - Specific focus on poimen-harness namespace
   - Looks for 4 terminated workflows

3. task-workflow-visibility.yaml: NEW Tekton task
   - Runs workflow visibility tests against live gateway
   - Sidecar deployment pattern
   - Publishes result + summary + workflow-count metrics

4. pipeline-sse-optimization.yaml: Updated
   - Added workflow-visibility-tests stage (runs after integration-tests)
   - Updated report-results to include workflow test results
   - Full pipeline now: integration → workflow-visibility → load → report

5. kustomization.yaml: Updated
   - Added task-workflow-visibility.yaml
   - Added workflow-visibility-test-script ConfigMap

This ensures that the deprecated /workflows endpoint replacement correctly
supports multi-tenant access via namespace specification in request payload.

k8s/tekton/pipeline-sse-optimization.yaml

@@ -30,10 +30,22 @@ spec:
     - name: gateway-port
       value: $(params.gateway-port)
   
+  # Workflow visibility tests (runs after integration tests pass)
+  - name: workflow-visibility-tests
+    runAfter:
+    - integration-tests
+    taskRef:
+      name: workflow-visibility-test
+    params:
+    - name: image
+      value: $(params.image)
+    - name: gateway-port
+      value: $(params.gateway-port)
+  
   # Performance load tests (runs after integration tests pass)
   - name: load-tests
     runAfter:
-    - integration-tests
+    - workflow-visibility-tests
     taskRef:
       name: load-test-sse-streaming
     params:
@@ -52,6 +64,7 @@ spec:
   - name: report-results
     runAfter:
     - load-tests
+    - workflow-visibility-tests
     taskSpec:
       description: "Report combined test results"
       params:
@@ -59,6 +72,10 @@ spec:
         type: string
       - name: integration-summary
         type: string
+      - name: workflow-result
+        type: string
+      - name: workflow-summary
+        type: string
       - name: load-result
         type: string
       - name: load-summary
@@ -70,27 +87,35 @@ spec:
         image: busybox
         script: |
           #!/bin/sh
-          echo "╔════════════════════════════════════════════════════╗"
-          echo "║        SSE Optimization Test Results (PR #26)      ║"
-          echo "╠════════════════════════════════════════════════════╣"
-          echo "║                                                    ║"
-          echo "║  Integration Tests:                                ║"
+          echo "╔═══════════════════════════════════════════════════════════╗"
+          echo "║      SSE Optimization + Workflow Tests (PR #26)          ║"
+          echo "╠═══════════════════════════════════════════════════════════╣"
+          echo "║                                                           ║"
+          echo "║  Integration Tests:                                       ║"
           echo "║    Status: $(params.integration-result)"
           echo "║    Summary: $(params.integration-summary)"
-          echo "║                                                    ║"
-          echo "║  Load Tests (Issues #31, #32, #33):                ║"
+          echo "║                                                           ║"
+          echo "║  Workflow Visibility (namespace pass-down):               ║"
+          echo "║    Status: $(params.workflow-result)"
+          echo "║    Summary: $(params.workflow-summary)"
+          echo "║                                                           ║"
+          echo "║  Load Tests (Issues #31, #32, #33):                       ║"
           echo "║    Status: $(params.load-result)"
           echo "║    Summary: $(params.load-summary)"
-          echo "║                                                    ║"
-          echo "║  Performance Metrics:                              ║"
+          echo "║                                                           ║"
+          echo "║  Performance Metrics:                                     ║"
           echo "║    $(params.load-metrics)"
-          echo "║                                                    ║"
-          echo "╚════════════════════════════════════════════════════╝"
+          echo "║                                                           ║"
+          echo "╚═══════════════════════════════════════════════════════════╝"
     params:
     - name: integration-result
       value: $(tasks.integration-tests.results.result)
     - name: integration-summary
       value: $(tasks.integration-tests.results.summary)
+    - name: workflow-result
+      value: $(tasks.workflow-visibility-tests.results.result)
+    - name: workflow-summary
+      value: $(tasks.workflow-visibility-tests.results.summary)
     - name: load-result
       value: $(tasks.load-tests.results.result)
     - name: load-summary