0.1.3

Changes

• Add BasicPlugin interface (Bmd\BasicPlugin) defining the mount(), setUrl(), and setPath() contract
• ResponsiveGridExtension now implements BasicPlugin
• Constructor accepts optional $url and $path parameters for flexible asset resolution when used as a Composer dependency
• buildPath() and buildUrl() now use injected URL/path properties
• Plugin bootstrap wrapped in named function (create_responsive_grid_extension_plugin())
• Removed version field from composer.json per Packagist convention
• Renamed responsive-grid-extension.php to plugin.php