Remove phone icon and improve horizontal overflow on mobile devices

Refactors Layout and Tasks components, removing the smartphone icon, disabling phone mode logic, and applying global CSS to prevent horizontal overflow across the application, particularly on mobile viewports.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 95e8aab4-f39f-4b48-aa57-a759ec15ba3d
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/95e8aab4-f39f-4b48-aa57-a759ec15ba3d/GEw2Z4s

client/src/index.css

@@ -64,11 +64,24 @@
     @apply font-sans antialiased bg-surface text-foreground;
     max-width: 100vw;
     height: 100%;
+    overflow-x: hidden;
   }
   
   #root {
     max-width: 100vw;
-    height: 100%;
+    min-height: 100%;
+    overflow-x: hidden;
+  }
+  
+  /* Éviter le débordement horizontal sur mobile */
+  * {
+    box-sizing: border-box;
+  }
+  
+  /* Forcer les conteneurs à ne pas déborder */
+  .container, .main-content, [data-testid*="task"] {
+    max-width: 100vw;
+    overflow-x: hidden;
   }
 
   /* Forcer la cohérence des largeurs de sidebar */