Add CI workflow to validate JSON files on push and PR (#1)

* Add GitHub Actions workflow to validate JSON files on PRs

Agent-Logs-Url: https://github.com/GroundServicesJP/GroundServicesJP_JSONService/sessions/fcd8c8bf-d92b-4c3e-a9d2-197984bffb63

Co-authored-by: anaflightsim <66984894+anaflightsim@users.noreply.github.com>

* Trigger JSON validation on push to all branches in addition to pull requests

Agent-Logs-Url: https://github.com/GroundServicesJP/GroundServicesJP_JSONService/sessions/ce4b38a4-acdf-46f0-9406-73d44a150cb7

Co-authored-by: anaflightsim <66984894+anaflightsim@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: anaflightsim <66984894+anaflightsim@users.noreply.github.com>

Author: Copilot

.github/workflows/validate-json.yml

@@ -0,0 +1,37 @@
+name: Validate JSON
+
+on:
+  push:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  validate-json:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Validate JSON files
+        run: |
+          failed=0
+          passed=0
+          while IFS= read -r -d '' file; do
+            if ! python3 -m json.tool "$file" > /dev/null 2>&1; then
+              echo "❌ Invalid JSON: $file"
+              python3 -m json.tool "$file" 2>&1 || true
+              failed=$((failed + 1))
+            else
+              echo "✅ Valid JSON: $file"
+              passed=$((passed + 1))
+            fi
+          done < <(find . -name '*.json' -not -path './.git/*' -print0)
+
+          echo ""
+          echo "Results: $passed passed, $failed failed"
+          if [ "$failed" -ne 0 ]; then
+            echo "::error::$failed JSON file(s) failed validation. See above for details."
+            exit 1
+          fi