feat: add multi-tenant system with properties, organizations, and public booking

Implement complete multi-property architecture:
- Properties (groups of spaces) with public/private visibility
- Property managers (many-to-many) with role-based permissions
- Organizations with member management
- Anonymous/guest booking support via public API (/api/public/*)
- Property-scoped spaces, bookings, and settings
- Frontend: property selector, organization management, public booking views
- Migration script and updated seed data

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

frontend/src/views/Users.vue

@@ -2,7 +2,7 @@
   <div class="users">
     <Breadcrumb :items="breadcrumbItems" />
     <div class="page-header">
-      <h2>Admin Dashboard - User Management</h2>
+      <h2>User Management</h2>
       <button class="btn btn-primary" @click="openCreateModal">
         <UserPlus :size="16" />
         Create New User
@@ -16,7 +16,8 @@
           <label for="filter-role">Filter by Role</label>
           <select id="filter-role" v-model="filterRole" @change="loadUsers">
             <option value="">All Roles</option>
-            <option value="admin">Admin</option>
+            <option value="admin">Superadmin</option>
+            <option value="manager">Manager</option>
             <option value="user">User</option>
           </select>
         </div>
@@ -57,8 +58,8 @@
               <td>{{ user.email }}</td>
               <td>{{ user.full_name }}</td>
               <td>
-                <span :class="['badge', user.role === 'admin' ? 'badge-admin' : 'badge-user']">
-                  {{ user.role }}
+                <span :class="['badge', user.role === 'admin' || user.role === 'superadmin' ? 'badge-admin' : user.role === 'manager' ? 'badge-manager' : 'badge-user']">
+                  {{ user.role === 'admin' ? 'superadmin' : user.role }}
                 </span>
               </td>
               <td>{{ user.organization || '-' }}</td>
@@ -140,7 +141,8 @@
             <label for="role">Role *</label>
             <select id="role" v-model="formData.role" required>
               <option value="user">User</option>
-              <option value="admin">Admin</option>
+              <option value="manager">Manager</option>
+              <option value="admin">Superadmin</option>
             </select>
           </div>
 
@@ -268,7 +270,8 @@ const handleSubmit = async () => {
         full_name: formData.value.full_name,
         password: formData.value.password,
         role: formData.value.role,
-        organization: formData.value.organization || undefined
+        organization: formData.value.organization || undefined,
+        timezone: 'UTC'
       })
       success.value = 'User created successfully!'
     }
@@ -389,6 +392,8 @@ onMounted(() => {
 
 .page-header h2 {
   margin: 0;
+  font-size: 28px;
+  font-weight: 700;
   color: var(--color-text-primary);
 }
 
@@ -593,6 +598,11 @@ onMounted(() => {
   color: var(--color-accent);
 }
 
+.badge-manager {
+  background: color-mix(in srgb, var(--color-warning) 15%, transparent);
+  color: var(--color-warning);
+}
+
 .badge-user {
   background: var(--color-bg-tertiary);
   color: var(--color-text-primary);
@@ -619,15 +629,18 @@ onMounted(() => {
 
 .modal-content {
   background: var(--color-surface);
-  border-radius: var(--radius-md);
-  padding: 24px;
+  border-radius: var(--radius-lg);
+  padding: 28px;
   max-width: 500px;
   width: 90%;
+  max-height: 90vh;
+  overflow-y: auto;
   box-shadow: var(--shadow-lg);
 }
 
 .modal-content h3 {
-  margin-bottom: 16px;
+  margin-top: 0;
+  margin-bottom: 20px;
   color: var(--color-text-primary);
 }