Inject frontend version as environment variable

lib/www/client/source/vue.config.js

@@ -1,4 +1,7 @@
 const webpack = require('webpack');
+const { execSync } = require('child_process');
+
+const gitDescribe = execSync('git describe --tags --always', { encoding: 'utf8' }).trim();
 
 module.exports = {
   "transpileDependencies": [
@@ -48,7 +51,11 @@ module.exports = {
       // https://github.com/webpack/changelog-v5/issues/10
       new webpack.ProvidePlugin({
         Buffer: ['buffer', 'Buffer'],
-      })
+      }),
+
+      new webpack.DefinePlugin({
+        'process.env.DOUGAL_FRONTEND_VERSION': JSON.stringify(gitDescribe),
+      }),
     ],
     module: {
       rules: [