Add Audible region config and user password change modal

Implements configurable Audible region selection in setup and admin settings, affecting all Audible API calls and triggering data refresh on change. Adds a user-facing 'Change Password' modal in the header for local users, moving password change from admin-only to all local users via a new /api/auth/change-password endpoint. Updates documentation, API routes, and context to support these features, and removes the old admin-only password change flow.

src/components/layout/Header.tsx

@@ -11,6 +11,7 @@ import Link from 'next/link';
 import { useAuth } from '@/contexts/AuthContext';
 import { Button } from '@/components/ui/Button';
 import { VersionBadge } from '@/components/ui/VersionBadge';
+import { ChangePasswordModal } from '@/components/ui/ChangePasswordModal';
 import { useSmartDropdownPosition } from '@/hooks/useSmartDropdownPosition';
 
 export function Header() {
@@ -18,8 +19,12 @@ export function Header() {
   const [showUserMenu, setShowUserMenu] = useState(false);
   const [showMobileMenu, setShowMobileMenu] = useState(false);
   const [showBookDate, setShowBookDate] = useState(false);
+  const [showChangePasswordModal, setShowChangePasswordModal] = useState(false);
   const { containerRef, dropdownRef, positionAbove, style } = useSmartDropdownPosition(showUserMenu);
 
+  // Check if user can change password (local users only)
+  const canChangePassword = user?.authProvider === 'local';
+
   // Check if BookDate is configured
   useEffect(() => {
     async function checkBookDate() {
@@ -85,6 +90,17 @@ export function Header() {
       >
         Profile
       </Link>
+      {canChangePassword && (
+        <button
+          onClick={() => {
+            setShowUserMenu(false);
+            setShowChangePasswordModal(true);
+          }}
+          className="w-full text-left px-4 py-2 text-gray-700 dark:text-gray-300 hover:bg-gray-100 dark:hover:bg-gray-700"
+        >
+          Change Password
+        </button>
+      )}
       <button
         onClick={() => {
           logout();
@@ -268,6 +284,12 @@ export function Header() {
 
       {/* User menu dropdown (rendered via portal) */}
       {typeof window !== 'undefined' && userMenuDropdown && createPortal(userMenuDropdown, document.body)}
+
+      {/* Change Password Modal */}
+      <ChangePasswordModal
+        isOpen={showChangePasswordModal}
+        onClose={() => setShowChangePasswordModal(false)}
+      />
     </header>
   );
 }