build: add changeset publishing automation

.changeset/README.md

@@ -0,0 +1,8 @@
+# Changesets
+
+Hello and welcome! This folder has been automatically generated by `@changesets/cli`, a build tool that works
+with multi-package repos, or single-package repos to help you version and publish your code. You can
+find the full documentation for it [in our repository](https://github.com/changesets/changesets)
+
+We have a quick list of common questions to get you started engaging with this project in
+[our documentation](https://github.com/changesets/changesets/blob/main/docs/common-questions.md)

.changeset/config.json

@@ -0,0 +1,11 @@
+{
+  "$schema": "https://unpkg.com/@changesets/config@3.0.0/schema.json",
+  "changelog": "@changesets/cli/changelog",
+  "commit": false,
+  "fixed": [],
+  "linked": [],
+  "access": "restricted",
+  "baseBranch": "main",
+  "updateInternalDependencies": "patch",
+  "ignore": []
+}

.changeset/dull-apricots-pay.md

@@ -0,0 +1,5 @@
+---
+"@badrap/libapp": patch
+---
+
+Add changeset publishing automation

.github/workflows/tests.yml → .github/workflows/ci.yml

@@ -1,6 +1,6 @@
-name: tests
+name: CI
 
-on: [push, pull_request]
+on: ["push", "pull_request"]
 
 jobs:
   build:
@@ -14,3 +14,4 @@ jobs:
       - run: npm ci
       - run: npm run lint
       - run: npm run typecheck
+      - run: npm test

.github/workflows/version-or-publish.yml

@@ -0,0 +1,47 @@
+name: Publish
+
+on:
+  push:
+    branches:
+      - main
+
+concurrency: ${{ github.workflow }}-${{ github.ref }}
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+      - run: npm ci
+      - run: npm run lint
+      - run: npm run typecheck
+      - run: npm test
+  publish:
+    needs: check
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      id-token: write
+      pull-requests: write
+      issues: read
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+      - name: Install dependencies
+        run: npm ci
+      - name: Create Release Pull Request or Publish to npm
+        id: changesets
+        uses: changesets/action@v1
+        with:
+          version: npm run bump
+          publish: npm run release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}