feat: Implement cache invalidation system for master dashboard

- Added HVAC_Master_Dashboard_Data::clear_cache() static method
- Clears all 5 cached metrics when events or user data changes
- Added WordPress hooks for automatic cache invalidation:
  - save_post/delete_post for events and ticket types
  - user_register/deleted_user for trainer changes
- Ensures data consistency while maintaining performance benefits
- Cache keys organized under 'hvac_master_dashboard' group

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

includes/class-hvac-community-events.php

@@ -140,6 +140,12 @@ class HVAC_Community_Events {
 		// Force correct content on master dashboard
 		add_filter('the_content', array($this, 'force_master_dashboard_content'), 1);
 		
+		// Cache invalidation hooks for master dashboard performance
+		add_action('save_post', array($this, 'clear_master_dashboard_cache'), 10, 1);
+		add_action('delete_post', array($this, 'clear_master_dashboard_cache'), 10, 1);
+		add_action('user_register', array($this, 'clear_master_dashboard_cache_on_user_change'));
+		add_action('deleted_user', array($this, 'clear_master_dashboard_cache_on_user_change'));
+		
 		// Authentication checks - these should eventually move to HVAC_Access_Control
 		add_action('template_redirect', array($this, 'check_event_summary_auth'));
 		add_action('template_redirect', array($this, 'check_email_attendees_auth'));
@@ -1119,4 +1125,36 @@ class HVAC_Community_Events {
 		));
 	}
 
+	/**
+	 * Clear master dashboard cache when posts are saved/deleted
+	 *
+	 * @param int $post_id Post ID
+	 */
+	public function clear_master_dashboard_cache($post_id) {
+		$post_type = get_post_type($post_id);
+		
+		// Clear cache for event-related post types or ticket types
+		$cache_trigger_types = [
+			'tribe_events',
+			'tec_tc_attendee', 
+			'tribe_tpp_attendees',
+			'tribe_rsvp_attendees'
+		];
+		
+		if (in_array($post_type, $cache_trigger_types)) {
+			if (class_exists('HVAC_Master_Dashboard_Data')) {
+				HVAC_Master_Dashboard_Data::clear_cache();
+			}
+		}
+	}
+
+	/**
+	 * Clear master dashboard cache when user data changes
+	 */
+	public function clear_master_dashboard_cache_on_user_change() {
+		if (class_exists('HVAC_Master_Dashboard_Data')) {
+			HVAC_Master_Dashboard_Data::clear_cache();
+		}
+	}
+
 } // End class HVAC_Community_Events

includes/class-hvac-master-dashboard-data.php

@@ -290,6 +290,26 @@ class HVAC_Master_Dashboard_Data {
 		return $total_revenue;
 	}
 
+	/**
+	 * Clear all cached master dashboard data
+	 * Should be called when events, tickets, or trainer data changes
+	 *
+	 * @return void
+	 */
+	public static function clear_cache() {
+		$cache_keys = [
+			'hvac_master_total_events_count',
+			'hvac_master_upcoming_events_count',
+			'hvac_master_past_events_count',
+			'hvac_master_total_tickets_sold',
+			'hvac_master_total_revenue'
+		];
+		
+		foreach ($cache_keys as $key) {
+			wp_cache_delete($key, 'hvac_master_dashboard');
+		}
+	}
+
 	/**
 	 * Get trainer statistics - count and individual performance data
 	 *