Add pkg-pr-new workflow for PR/commit publishing

Enables automatic publishing of any commit or PR to pkg.pr.new,
allowing consumers to install directly from git commits:

npm install https://pkg.pr.new/modelcontextprotocol/ext-apps/@modelcontextprotocol/ext-apps@<commit-or-pr>

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: jerome3o-anthropic

.github/workflows/publish.yml

@@ -0,0 +1,23 @@
+name: Publish Any Commit
+permissions:
+  contents: read
+on:
+  pull_request:
+  push:
+    branches:
+      - "**"
+    tags:
+      - "!**"
+
+jobs:
+  pkg-publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+      - run: npm ci
+      - run: npm run build
+      - run: npx pkg-pr-new publish