fix: booking modal positioning — use portal to render in document.body

Also make header full-width (remove max-w-6xl constraint).

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

src/components/ui/BookingModal.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useState, useEffect, useCallback } from "react";
+import { createPortal } from "react-dom";
 import { X, Instagram, Send, CheckCircle, Phone } from "lucide-react";
 import { siteContent } from "@/data/content";
 
@@ -84,7 +85,7 @@ export function BookingModal({ open, onClose }: BookingModalProps) {
 
   if (!open) return null;
 
-  return (
+  return createPortal(
     <div
       className="modal-overlay fixed inset-0 z-50 flex items-center justify-center p-4"
       onClick={handleClose}
@@ -193,6 +194,7 @@ export function BookingModal({ open, onClose }: BookingModalProps) {
           </>
         )}
       </div>
-    </div>
+    </div>,
+    document.body
   );
 }