0.2.0

• New shortcode attributes show_past="true|false" to control visibility of "Past" and "Upcoming" toggle buttons (defaults to true if past bookings are enabled in settings).
• New shortcode attribute dark_mode="true|false" to enable/disable dark mode per shortcode instance (overrides settings, defaults to false).
• New shortcode generator located in the Settings > Stagent page under the "Shortcode Generator" tab.
• Added nonce security, migrated inline JS to stagent-admin.js, refined stagent_booking_widget validation, and streamlined shortcode generator UI for better usability and compliance.
• Enhanced template security with sanitization/escaping, added type safety, updated README with full $atts docs, fixed filename mismatches and 403 errors, and ensured widget display consistency.