ci: annotate openapi-ts warnings with a problem matcher

Author: ariesclark

.github/matchers/openapi-ts.json

@@ -0,0 +1,15 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "openapi-ts",
+      "severity": "warning",
+      "pattern": [
+        {
+          "regexp": "^❗\\S*\\s(\\w+) warning: (.+)$",
+          "code": 1,
+          "message": 2
+        }
+      ]
+    }
+  ]
+}

.github/workflows/ci.yaml

@@ -45,7 +45,10 @@ jobs:
           runtime: node@24
           cache: true
 
-      - run: pnpm generate
+      - run: |
+          echo "::add-matcher::$GITHUB_WORKSPACE/.github/matchers/openapi-ts.json"
+          pnpm generate
+          echo "::remove-matcher owner=openapi-ts::"
 
       - id: version
         run: |