chore: remove unused legacy departure card styles and dead code

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

public/js/components/DeparturesManager.js

@@ -244,6 +244,8 @@ class DeparturesManager {
         return { countdownText, countdownClass };
     }
 
+    // --- Legacy single-site display methods (fallback if API returns data.departures instead of data.sites) ---
+
     /**
      * Create a departure card element (legacy format)
      * @param {Object} departure - Departure object
@@ -389,8 +391,11 @@ class DeparturesManager {
         });
     }
 
+    // --- Legacy single-site display methods (continued) ---
+
     /**
-     * Display departures in the UI
+     * Display departures in the UI (legacy single-site path)
+     * Called when API returns data.departures instead of data.sites.
      * @param {Array} departures - Array of departure objects
      */
     displayDepartures(departures) {
@@ -414,7 +419,7 @@ class DeparturesManager {
     }
 
     /**
-     * Update existing cards or add new ones
+     * Update existing cards or add new ones (legacy single-site path)
      * @param {Array} newDepartures - Array of new departure objects
      */
     updateExistingCards(newDepartures) {
@@ -460,7 +465,7 @@ class DeparturesManager {
     }
 
     /**
-     * Update card content
+     * Update card content (legacy single-site path)
      * @param {HTMLElement} card - Card element
      * @param {Object} departure - Departure object
      */
@@ -482,6 +487,8 @@ class DeparturesManager {
         }
     }
 
+    // --- End of legacy single-site display methods ---
+
     /**
      * Add highlight effect to element
      * @param {HTMLElement} element - Element to highlight