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/booking.py

@@ -1,8 +1,8 @@
 """Booking schemas for request/response."""
 from datetime import datetime, date
-from typing import Optional
+from typing import Any, Optional
 
-from pydantic import BaseModel, Field, field_validator
+from pydantic import BaseModel, Field, field_validator, model_validator
 
 
 class BookingCalendarPublic(BaseModel):
@@ -21,7 +21,7 @@ class BookingCalendarAdmin(BaseModel):
     """Full booking data for admins (calendar view)."""
 
     id: int
-    user_id: int
+    user_id: int | None = None
     space_id: int
     start_datetime: datetime
     end_datetime: datetime
@@ -50,7 +50,7 @@ class BookingResponse(BaseModel):
     """Schema for booking response after creation."""
 
     id: int
-    user_id: int
+    user_id: int | None = None
     space_id: int
     start_datetime: datetime
     end_datetime: datetime
@@ -58,6 +58,10 @@ class BookingResponse(BaseModel):
     title: str
     description: str | None
     created_at: datetime
+    guest_name: str | None = None
+    guest_email: str | None = None
+    guest_organization: str | None = None
+    is_anonymous: bool = False
     # Timezone-aware formatted strings (optional, set by endpoint)
     start_datetime_tz: Optional[str] = None
     end_datetime_tz: Optional[str] = None
@@ -79,6 +83,10 @@ class BookingResponse(BaseModel):
             title=booking.title,
             description=booking.description,
             created_at=booking.created_at,
+            guest_name=booking.guest_name,
+            guest_email=booking.guest_email,
+            guest_organization=booking.guest_organization,
+            is_anonymous=booking.is_anonymous,
             start_datetime_tz=format_datetime_tz(booking.start_datetime, user_timezone),
             end_datetime_tz=format_datetime_tz(booking.end_datetime, user_timezone)
         )
@@ -90,9 +98,20 @@ class SpaceInBooking(BaseModel):
     id: int
     name: str
     type: str
+    property_id: int | None = None
+    property_name: str | None = None
 
     model_config = {"from_attributes": True}
 
+    @model_validator(mode="wrap")
+    @classmethod
+    def extract_property_name(cls, data: Any, handler: Any) -> "SpaceInBooking":
+        """Extract property_name from ORM relationship."""
+        instance = handler(data)
+        if instance.property_name is None and hasattr(data, 'property') and data.property:
+            instance.property_name = data.property.name
+        return instance
+
 
 class BookingWithSpace(BaseModel):
     """Booking with associated space details for user's booking list."""
@@ -127,14 +146,18 @@ class BookingPendingDetail(BaseModel):
     id: int
     space_id: int
     space: SpaceInBooking
-    user_id: int
-    user: UserInBooking
+    user_id: int | None = None
+    user: UserInBooking | None = None
     start_datetime: datetime
     end_datetime: datetime
     status: str
     title: str
     description: str | None
     created_at: datetime
+    guest_name: str | None = None
+    guest_email: str | None = None
+    guest_organization: str | None = None
+    is_anonymous: bool = False
 
     model_config = {"from_attributes": True}
 
@@ -242,3 +265,16 @@ class BookingReschedule(BaseModel):
 
     start_datetime: datetime
     end_datetime: datetime
+
+
+class AnonymousBookingCreate(BaseModel):
+    """Schema for anonymous/guest booking creation."""
+
+    space_id: int
+    start_datetime: datetime
+    end_datetime: datetime
+    title: str = Field(..., min_length=1, max_length=200)
+    description: str | None = None
+    guest_name: str = Field(..., min_length=1)
+    guest_email: str = Field(..., min_length=1)
+    guest_organization: str | None = None