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>

backend/app/schemas/property.py

@@ -0,0 +1,82 @@
+"""Property schemas."""
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class PropertyCreate(BaseModel):
+    name: str = Field(..., min_length=1)
+    description: str | None = None
+    address: str | None = None
+    is_public: bool = True
+
+
+class PropertyUpdate(BaseModel):
+    name: str | None = None
+    description: str | None = None
+    address: str | None = None
+    is_public: bool | None = None
+
+
+class PropertyManagerInfo(BaseModel):
+    user_id: int
+    full_name: str
+    email: str
+
+
+class PropertyResponse(BaseModel):
+    id: int
+    name: str
+    description: str | None = None
+    address: str | None = None
+    is_public: bool
+    is_active: bool
+    created_at: datetime
+    space_count: int = 0
+    managers: list[PropertyManagerInfo] = []
+
+    model_config = {"from_attributes": True}
+
+
+class PropertyWithSpaces(PropertyResponse):
+    spaces: list = []
+
+
+class PropertyAccessCreate(BaseModel):
+    user_id: int | None = None
+    organization_id: int | None = None
+
+
+class PropertyAccessResponse(BaseModel):
+    id: int
+    property_id: int
+    user_id: int | None = None
+    organization_id: int | None = None
+    granted_by: int | None = None
+    user_name: str | None = None
+    user_email: str | None = None
+    organization_name: str | None = None
+    created_at: datetime
+
+    model_config = {"from_attributes": True}
+
+
+class PropertySettingsUpdate(BaseModel):
+    working_hours_start: int | None = None
+    working_hours_end: int | None = None
+    min_duration_minutes: int | None = None
+    max_duration_minutes: int | None = None
+    max_bookings_per_day_per_user: int | None = None
+    require_approval: bool = True
+    min_hours_before_cancel: int | None = None
+
+
+class PropertySettingsResponse(PropertySettingsUpdate):
+    id: int
+    property_id: int
+
+    model_config = {"from_attributes": True}
+
+
+class PropertyStatusUpdate(BaseModel):
+    is_active: bool