add actions and workflow

Author: mikeharder

.github/actions/install-deps-github-script/action.yaml

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+name: Install dependencies for github-script actions
+description: Installs dependencies for github-script actions
+
+runs:
+  using: composite
+
+  steps:
+    - uses: ./.github/actions/setup-node-install-deps
+      with:
+        # actions/github-script@v8 uses Node 24
+        node-version: 24.x
+        # "--no-audit": improves performance
+        # "--no-fund": improves performance
+        # "--prefer-offline": improves performance
+        # "--omit dev": not needed at runtime, improves performance
+        install-command: "npm ci --no-audit --no-fund --prefer-offline --omit dev"
+        working-directory: ./.github

.github/actions/setup-node-install-deps/action.yaml

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+name: Setup Node and install dependencies
+description: Uses specified Node version and installs dependencies (typically using "npm")
+
+inputs:
+  node-version:
+    description: "Node version to use"
+    default: 24.x
+  install-command:
+    description: "Command to install dependencies"
+    default: "npm ci --no-audit --no-fund --prefer-offline"
+  working-directory:
+    description: "Working directory"
+    default: "."
+
+runs:
+  using: "composite"
+
+  steps:
+    - uses: actions/setup-node@v6
+      with:
+        node-version: ${{ inputs.node-version }}
+        cache: "npm"
+        cache-dependency-path: ${{ inputs.working-directory }}/package-lock.json
+
+    - run: |
+        echo "::group::$INSTALL_COMMAND"
+        $INSTALL_COMMAND
+        echo "::endgroup::"
+      shell: bash
+      env:
+        INSTALL_COMMAND: ${{ inputs.install-command }}
+      working-directory: ${{ inputs.working-directory }}
+
+    - run: |
+        echo "::group::npm ls -a"
+        npm ls -a || true
+        echo "::endgroup::"
+      shell: bash
+      working-directory: ${{ inputs.working-directory }}

.github/matchers/actionlint.json

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+{
+  "problemMatcher": [
+    {
+      "owner": "actionlint",
+      "pattern": [
+        {
+          "regexp": "^(?:\\x1b\\[\\d+m)?(.+?)(?:\\x1b\\[\\d+m)*:(?:\\x1b\\[\\d+m)*(\\d+)(?:\\x1b\\[\\d+m)*:(?:\\x1b\\[\\d+m)*(\\d+)(?:\\x1b\\[\\d+m)*: (?:\\x1b\\[\\d+m)*(.+?)(?:\\x1b\\[\\d+m)* \\[(.+?)\\]$",
+          "file": 1,
+          "line": 2,
+          "column": 3,
+          "message": 4,
+          "code": 5
+        }
+      ]
+    }
+  ]
+}

.github/workflows/github-test.yaml

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+name: GitHub Actions - Test
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - .github/**
+  pull_request:
+    paths:
+      - .github/**
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        folder: [.github, .github/shared]
+        os: [ubuntu, windows]
+
+    runs-on: ${{ fromJSON('{"ubuntu":"ubuntu-24.04", "windows":"windows-2022"}')[matrix.os] }}
+
+    defaults:
+      run:
+        working-directory: ./${{ matrix.folder }}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          sparse-checkout: |
+            .github
+
+      - if: ${{ matrix.folder == '.github' }}
+        name: Install dependencies for github-script actions
+        uses: ./.github/actions/install-deps-github-script
+
+      - if: ${{ matrix.folder == '.github' }}
+        name: Verify all modules are importable
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const { join } = await import("path");
+            const { pathToFileURL } = await import("url");
+            const fullPath = join(process.env.GITHUB_WORKSPACE, ".github", "workflows", "src", "github-test.js");
+            const { default: importAllModules } = await import(pathToFileURL(fullPath).href);
+            await importAllModules({ core });
+
+      - name: Install dev deps
+        uses: ./.github/actions/setup-node-install-deps
+        with:
+          # actions/github-script@v8 uses Node 24
+          node-version: 24.x
+          working-directory: ./${{ matrix.folder }}
+
+      - run: npm run test:ci
+
+      - run: npm run lint
+
+      - run: npm run format:check:ci
+
+      # Content copied from https://raw.githubusercontent.com/rhysd/actionlint/2ab3a12c7848f6c15faca9a92612ef4261d0e370/.github/actionlint-matcher.json
+      - if: ${{ matrix.folder == '.github' && matrix.os == 'ubuntu'}}
+        name: Add ActionLint Problem Matcher
+        run: echo "::add-matcher::.github/matchers/actionlint.json"
+
+      - if: ${{ matrix.folder == '.github' && matrix.os == 'ubuntu'}}
+        name: Lint workflows
+        uses: docker://rhysd/actionlint:1.7.12@sha256:b1934ee5f1c509618f2508e6eb47ee0d3520686341fec936f3b79331f9315667
+        with:
+          args: -color -verbose