Add size-limit bundle-size checks on PRs

Add size-limit with `@size-limit/preset-small-lib` to enforce a 160 kB budget on the main entry point. A GitHub Actions workflow builds the project on each PR, runs size-limit from local node_modules (bypassing npx version mismatch with the old andresz1 action), and posts a comment with current sizes. Fails the check if any budget is exceeded.

Closes #11

Author: zeevdr

.github/workflows/size.yml

@@ -0,0 +1,67 @@
+# Bundle-size check for pull requests.
+#
+# Runs size-limit from local node_modules (avoids npx version mismatch).
+# Posts a PR comment with current sizes and fails if any budget is exceeded.
+
+name: Size
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    branches: [main]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  size:
+    name: Bundle size
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: "22"
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build
+        run: npm run build
+
+      - name: Check bundle size
+        id: size
+        run: |
+          ./node_modules/.bin/size-limit --json > size-output.json
+          cat size-output.json
+
+      - name: Post size comment
+        if: always() && steps.size.conclusion != 'skipped'
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const fs = require('fs');
+            if (!fs.existsSync('size-output.json')) return;
+            let results;
+            try { results = JSON.parse(fs.readFileSync('size-output.json', 'utf8')); }
+            catch { return; }
+            const rows = results.map(r => {
+              const status = r.exceeded ? '❌' : '✅';
+              const size = r.size != null ? `${(r.size / 1024).toFixed(1)} kB` : 'n/a';
+              const limit = r.sizeLimit || 'none';
+              return `| ${r.name || r.path} | ${size} | ${limit} | ${status} |`;
+            }).join('\n');
+            const body = `## Bundle size\n\n| Entry | Size | Budget | Status |\n|-------|------|--------|--------|\n${rows}`;
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body
+            });

.size-limit.js

@@ -0,0 +1,10 @@
+export default [
+  {
+    path: "dist/index.js",
+    limit: "160 kB",
+    modifyEsbuildConfig(config) {
+      config.platform = "node";
+      return config;
+    },
+  },
+];