Add minify build script and generate .min CSS/JS; rename position to brand-aside

Build tooling:
- Add package.json with clean-css and terser dev dependencies
- Add scripts/minify.js: reads joomla.asset.json, auto-detects source/.min
  pairs, and minifies all template-owned CSS and JS files
- Add node_modules/ to .gitignore

Generated .min files (all 6 manifest pairs):
- css/template.min.css      (17.8% saved)
- css/editor.min.css        (49.4% saved)
- css/theme/light.standard.min.css  (13.1% saved)
- css/theme/dark.standard.min.css   (14.4% saved)
- js/template.min.js        (58.2% saved)
- js/gtm.min.js             (62.3% saved)

Rename: header-aside → brand-aside (position, CSS class, language keys)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,12 @@
+{
+	"name": "mokocassiopeia-build",
+	"private": true,
+	"description": "Build tooling for MokoCassiopeia Joomla template",
+	"scripts": {
+		"minify": "node scripts/minify.js"
+	},
+	"devDependencies": {
+		"clean-css": "^5.3.3",
+		"terser": "^5.39.0"
+	}
+}