feat(11-01): create sites table migration, model, and schemas

- Add migration 030 with sites table, RLS policy, and device site_id FK
- Add Site SQLAlchemy model with tenant isolation
- Add site_id nullable FK and relationship to Device model
- Add sites relationship to Tenant model
- Register Site in models __init__.py
- Add SiteCreate, SiteUpdate, SiteResponse, SiteListResponse schemas

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -13,6 +13,7 @@ from app.models.device import (
 from app.models.alert import AlertRule, NotificationChannel, AlertRuleChannel, AlertEvent
 from app.models.firmware import FirmwareVersion, FirmwareUpgradeJob
 from app.models.config_template import ConfigTemplate, ConfigTemplateTag, TemplatePushJob
+from app.models.site import Site
 from app.models.audit_log import AuditLog
 from app.models.maintenance_window import MaintenanceWindow
 from app.models.api_key import ApiKey
@@ -28,6 +29,7 @@ __all__ = [
     "DeviceGroupMembership",
     "DeviceTagAssignment",
     "DeviceStatus",
+    "Site",
     "AlertRule",
     "NotificationChannel",
     "AlertRuleChannel",

backend/app/models/device.py

@@ -101,6 +101,13 @@ class Device(Base):
     tag_assignments: Mapped[list["DeviceTagAssignment"]] = relationship(
         "DeviceTagAssignment", back_populates="device", cascade="all, delete-orphan"
     )
+    site_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("sites.id", ondelete="SET NULL"),
+        nullable=True,
+        index=True,
+    )
+    site: Mapped["Site"] = relationship("Site", back_populates="devices")  # type: ignore[name-defined]
 
     def __repr__(self) -> str:
         return f"<Device id={self.id} hostname={self.hostname!r} tenant_id={self.tenant_id}>"

backend/app/models/site.py

@@ -0,0 +1,49 @@
+"""Site model -- physical location grouping for devices."""
+
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, Float, ForeignKey, String, Text, UniqueConstraint, func
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base
+
+
+class Site(Base):
+    __tablename__ = "sites"
+    __table_args__ = (UniqueConstraint("tenant_id", "name", name="uq_sites_tenant_name"),)
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        primary_key=True,
+        default=uuid.uuid4,
+        server_default=func.gen_random_uuid(),
+    )
+    tenant_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("tenants.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    name: Mapped[str] = mapped_column(String(255), nullable=False)
+    latitude: Mapped[float | None] = mapped_column(Float, nullable=True)
+    longitude: Mapped[float | None] = mapped_column(Float, nullable=True)
+    address: Mapped[str | None] = mapped_column(Text, nullable=True)
+    elevation: Mapped[float | None] = mapped_column(Float, nullable=True)
+    notes: Mapped[str | None] = mapped_column(Text, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+    )
+
+    # Relationships
+    tenant: Mapped["Tenant"] = relationship("Tenant", back_populates="sites")  # type: ignore[name-defined]
+    devices: Mapped[list["Device"]] = relationship(  # type: ignore[name-defined]
+        "Device", back_populates="site", foreign_keys="[Device.site_id]"
+    )
+
+    def __repr__(self) -> str:
+        return f"<Site id={self.id} name={self.name!r} tenant_id={self.tenant_id}>"

backend/app/models/tenant.py

@@ -52,6 +52,9 @@ class Tenant(Base):
     device_tags: Mapped[list["DeviceTag"]] = relationship(
         "DeviceTag", back_populates="tenant", passive_deletes=True
     )  # type: ignore[name-defined]
+    sites: Mapped[list["Site"]] = relationship(
+        "Site", back_populates="tenant", cascade="all, delete-orphan"
+    )  # type: ignore[name-defined]
 
     def __repr__(self) -> str:
         return f"<Tenant id={self.id} name={self.name!r}>"