Improve calendar weekend styling for better visual clarity

Apply custom CSS classes and inline styles to the Calendar component to ensure weekend days are consistently styled with a light gray background, addressing an issue where weekend backgrounds were not rendering correctly.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: cc2d271b-82f0-4d6a-9302-a0b067ffb429
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/cc2d271b-82f0-4d6a-9302-a0b067ffb429/AvJXlQr

client/src/index.css

@@ -325,3 +325,29 @@ button[aria-current="date"]:focus-visible,
   outline: 2px solid #2563eb !important;
   outline-offset: 2px !important;
 }
+
+/* Style pour les weekends dans le calendrier - FOND GRIS CLAIR */
+.weekend-day,
+.rdp-day.weekend-day,
+.rdp-button.weekend-day {
+  background-color: #f3f4f6 !important; /* bg-gray-100 */
+}
+
+.dark .weekend-day,
+.dark .rdp-day.weekend-day,
+.dark .rdp-button.weekend-day {
+  background-color: #1f2937 !important; /* bg-gray-800 */
+}
+
+/* Forcer le style weekend sur tous les samedis et dimanches */
+[data-day-weekend="true"],
+button[data-day-weekend="true"],
+.rdp-day[data-day-weekend="true"] {
+  background-color: #f3f4f6 !important;
+}
+
+.dark [data-day-weekend="true"],
+.dark button[data-day-weekend="true"],
+.dark .rdp-day[data-day-weekend="true"] {
+  background-color: #1f2937 !important;
+}