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/components/PropertySelector.vue

@@ -0,0 +1,87 @@
+<template>
+  <div v-if="authStore.isAdminOrManager && propertyStore.properties.length > 0" class="property-selector">
+    <label class="selector-label">
+      <Landmark :size="14" />
+      <span>Property</span>
+    </label>
+    <select
+      :value="propertyStore.currentPropertyId"
+      @change="handleChange"
+      class="property-select"
+    >
+      <option :value="null">All Properties</option>
+      <option
+        v-for="prop in propertyStore.properties"
+        :key="prop.id"
+        :value="prop.id"
+      >
+        {{ prop.name }}
+      </option>
+    </select>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { onMounted } from 'vue'
+import { useAuthStore } from '@/stores/auth'
+import { usePropertyStore } from '@/stores/property'
+import { Landmark } from 'lucide-vue-next'
+
+const authStore = useAuthStore()
+const propertyStore = usePropertyStore()
+
+const handleChange = (event: Event) => {
+  const value = (event.target as HTMLSelectElement).value
+  propertyStore.setCurrentProperty(value ? Number(value) : null)
+}
+
+onMounted(() => {
+  if (authStore.isAdminOrManager && propertyStore.properties.length === 0) {
+    propertyStore.fetchMyProperties()
+  }
+})
+</script>
+
+<style scoped>
+.property-selector {
+  padding: 0.75rem 1rem;
+  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
+}
+
+.selector-label {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  font-size: 11px;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+  color: var(--sidebar-text);
+  opacity: 0.6;
+  margin-bottom: 6px;
+}
+
+.property-select {
+  width: 100%;
+  padding: 8px 10px;
+  border-radius: var(--radius-sm);
+  border: 1px solid rgba(255, 255, 255, 0.15);
+  background: var(--sidebar-hover-bg);
+  color: var(--sidebar-text-active);
+  font-size: 13px;
+  font-weight: 500;
+  cursor: pointer;
+  outline: none;
+  transition: border-color var(--transition-fast);
+}
+
+.property-select:focus {
+  border-color: var(--color-accent);
+  box-shadow: 0 0 0 2px color-mix(in srgb, var(--color-accent) 20%, transparent);
+}
+
+.property-select option {
+  background: var(--color-surface);
+  color: var(--color-text-primary);
+}
+</style>