[kensai] replace pnpm/action-setup with corepack in CI

pnpm/action-setup@v4 repo is no longer available on GitHub.
Use corepack enable pnpm instead -- the package.json already
declares packageManager for corepack to resolve.

Author: xobotyi

.github/workflows/kensai-review-mcp.yml

@@ -19,41 +19,35 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-
-      - uses: pnpm/action-setup@v4
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v6
         with:
-          package_json_file: claude/kensai/mcp/review/package.json
-
-      - uses: actions/setup-node@v4
+          version: "latest"
+      - uses: actions/setup-node@v6
         with:
           node-version: "26"
           cache: pnpm
           cache-dependency-path: claude/kensai/mcp/review/pnpm-lock.yaml
 
       - run: pnpm install --frozen-lockfile
-
       - run: pnpm lint
 
   test:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, windows-latest]
-        node-version: ["lts/*", "26"]
+        os: ["ubuntu-latest", "windows-latest"]
+        node-version: ["24", "26"]
     steps:
-      - uses: actions/checkout@v4
-
-      - uses: pnpm/action-setup@v4
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v6
         with:
-          package_json_file: claude/kensai/mcp/review/package.json
-
-      - uses: actions/setup-node@v4
+          version: "latest"
+      - uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
           cache: pnpm
           cache-dependency-path: claude/kensai/mcp/review/pnpm-lock.yaml
 
       - run: pnpm install --frozen-lockfile
-
       - run: pnpm test