Add Prettier for TypeScript formatting

- Install prettier
- Configure .prettierrc.json and .prettierignore
- Add npm scripts: format, format:check
- Add Makefile target: format-frontend
- Format all frontend files

frontend/app/utils/appointment.ts

@@ -10,7 +10,7 @@ export interface StatusDisplay {
 
 /**
  * Get display information for an appointment status.
- * 
+ *
  * @param status - The appointment status string
  * @param isOwnView - If true, uses "Cancelled by you" instead of "Cancelled by user"
  */
@@ -25,9 +25,12 @@ export function getStatusDisplay(status: string, isOwnView: boolean = false): St
         textColor: "#f87171",
       };
     case "cancelled_by_admin":
-      return { text: "Cancelled by admin", bgColor: "rgba(239, 68, 68, 0.2)", textColor: "#f87171" };
+      return {
+        text: "Cancelled by admin",
+        bgColor: "rgba(239, 68, 68, 0.2)",
+        textColor: "#f87171",
+      };
     default:
       return { text: status, bgColor: "rgba(255,255,255,0.1)", textColor: "rgba(255,255,255,0.6)" };
   }
 }
-