fix(ci): use nohup for background mockd to survive step boundaries

GitHub Actions kills background processes between run steps. Use
nohup + redirect to keep mockd alive for subsequent test steps.

Author: zach-snell

.github/workflows/ci.yaml

@@ -39,6 +39,19 @@ jobs:
         env:
           GH_TOKEN: ${{ github.token }}
 
+      - name: Start mockd
+        run: |
+          CONFIG_DIR=$(dirname ${{ matrix.sample.config }})
+          cd "$CONFIG_DIR"
+          nohup mockd start -c mockd.yaml --no-auth --log-level error > /tmp/mockd.log 2>&1 &
+          echo $! > /tmp/mockd.pid
+          for i in $(seq 1 30); do
+            curl -sf http://localhost:4290/health > /dev/null 2>&1 && break
+            sleep 1
+          done
+          curl -sf http://localhost:4290/health
+          mockd list --json --admin-url http://localhost:4290 | python3 -c "import sys,json; d=json.load(sys.stdin); print(f'Loaded {len(d)} mocks')"
+
       - name: Run test script
         run: |
           CONFIG_DIR=$(dirname ${{ matrix.sample.config }})
@@ -47,7 +60,7 @@ jobs:
 
       - name: Stop mockd
         if: always()
-        run: mockd stop 2>/dev/null || true
+        run: pkill -f mockd || true
 
   validate-digital-twins:
     name: Validate Digital Twins
@@ -103,8 +116,8 @@ jobs:
         run: |
           CONFIG_DIR=$(dirname ${{ matrix.sample.config }})
           cd "$CONFIG_DIR"
-          mockd start -c mockd.yaml --no-auth --log-level error &
-          cd -
+          nohup mockd start -c mockd.yaml --no-auth --log-level error > /tmp/mockd.log 2>&1 &
+          echo $! > /tmp/mockd.pid
           for i in $(seq 1 60); do
             curl -sf http://localhost:4290/health > /dev/null 2>&1 && break
             sleep 1