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>

src/language/en-GB/tpl_mokocassiopeia.sys.ini

@@ -18,7 +18,7 @@ TPL_MOKOCASSIOPEIA_MOD_MENU_LAYOUT_COLLAPSE_METISMENU="Collapsible Dropdown"
 TPL_MOKOCASSIOPEIA_MOD_MENU_LAYOUT_DROPDOWN_METISMENU="Dropdown"
 TPL_MOKOCASSIOPEIA_POSITION_BANNER="Banner"
 TPL_MOKOCASSIOPEIA_POSITION_BELOW_TOP="Below Top"
-TPL_MOKOCASSIOPEIA_POSITION_HEADER_ASIDE="Header Aside"
+TPL_MOKOCASSIOPEIA_POSITION_BRAND_ASIDE="Brand Aside"
 TPL_MOKOCASSIOPEIA_POSITION_BOTTOM_A="Bottom-A"
 TPL_MOKOCASSIOPEIA_POSITION_BOTTOM_B="Bottom-B"
 TPL_MOKOCASSIOPEIA_POSITION_BREADCRUMBS="Breadcrumbs"

src/language/en-US/tpl_mokocassiopeia.sys.ini

@@ -18,7 +18,7 @@ TPL_MOKOCASSIOPEIA_MOD_MENU_LAYOUT_COLLAPSE_METISMENU="Collapsible Dropdown"
 TPL_MOKOCASSIOPEIA_MOD_MENU_LAYOUT_DROPDOWN_METISMENU="Dropdown"
 TPL_MOKOCASSIOPEIA_POSITION_BANNER="Banner"
 TPL_MOKOCASSIOPEIA_POSITION_BELOW_TOP="Below Top"
-TPL_MOKOCASSIOPEIA_POSITION_HEADER_ASIDE="Header Aside"
+TPL_MOKOCASSIOPEIA_POSITION_BRAND_ASIDE="Brand Aside"
 TPL_MOKOCASSIOPEIA_POSITION_BOTTOM_A="Bottom-A"
 TPL_MOKOCASSIOPEIA_POSITION_BOTTOM_B="Bottom-B"
 TPL_MOKOCASSIOPEIA_POSITION_BREADCRUMBS="Breadcrumbs"