add build workflow and update README with build status badge

.gitea/workflows/build.yml

@@ -0,0 +1,31 @@
+name: build
+
+on:
+  push:
+    paths:
+      - .gitea/workflows/build.yml
+      - 'src/**'
+      - package.json
+      - package-lock.json
+      - tsconfig.json
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: '24'
+      - name: Install dependencies
+        run: npm ci
+      - name: Build project
+        run: npm run build
+      - name: Publish package
+        run: |
+          npm config set @slawek:registry=https://gitea.koszewscy.waw.pl/api/packages/slawek/npm/
+          npm config set -- '//gitea.koszewscy.waw.pl/api/packages/slawek/npm/:_authToken' "${{ secrets.CI_TOKEN }}"
+          npm publish --access public

README.md

@@ -1,5 +1,7 @@
 # SK Tools
 
+[![test](https://gitea.koszewscy.waw.pl/slawek/sk-tools/actions/workflows/build.yml/badge.svg)](https://gitea.koszewscy.waw.pl/slawek/sk-tools/actions?workflow=build.yml)
+
 Generic utilities shared across Slawek's tool packages.
 
 ## Scope