ci: add a reusable spec check the specification repo can call

Author: ariesclark

.github/workflows/spec-check.yaml

@@ -0,0 +1,48 @@
+on:
+  workflow_call:
+    inputs:
+      artifact:
+        description: Artifact holding the bundled specification, uploaded by the caller.
+        required: false
+        type: string
+        default: openapi.json
+      ref:
+        description: Ref of this repository to build against the specification.
+        required: false
+        type: string
+        default: main
+
+name: Spec check
+
+jobs:
+  build:
+    name: javascript
+    runs-on: ubuntu-latest
+    steps:
+      # The caller supplies the workflow context, so this repository has to be
+      # checked out by name rather than implicitly.
+      - uses: actions/checkout@v7
+        with:
+          repository: vrchatapi/vrchatapi-javascript
+          ref: ${{ inputs.ref }}
+
+      - uses: pnpm/action-setup@v6
+        with:
+          version: 10
+          run_install: false
+
+      - uses: actions/setup-node@v7
+        with:
+          node-version: 24
+          cache: pnpm
+
+      # `openapi-ts.config.ts` reads ./openapi.json, which `pnpm build`
+      # regenerates the client from.
+      - uses: actions/download-artifact@v8
+        with:
+          name: ${{ inputs.artifact }}
+          path: .
+
+      - run: pnpm install
+
+      - run: pnpm build