feat: host inventory (agent.inventory), host detail page, UI columns

Store hardware/software snapshots on hosts; warn on hardware changes. Host card from Hosts list. Add agent version column to Events/Overview; rename Hosts table columns and sort by status.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/schemas/list_models.py

@@ -8,6 +8,7 @@ class HostSummary(BaseModel):
     hostname: str
     display_name: str | None
     os_family: str
+    os_version: str | None = None
     product: str
     product_version: str | None
     ipv4: str | None
@@ -15,11 +16,22 @@ class HostSummary(BaseModel):
     event_count: int | None = None
     last_heartbeat_at: datetime | None = None
     last_daily_report_at: datetime | None = None
+    last_inventory_at: datetime | None = None
     agent_status: str = "unknown"
 
     model_config = {"from_attributes": True}
 
 
+class HostDetail(HostSummary):
+    agent_instance_id: str | None = None
+    ipv6: str | None = None
+    tags: list | None = None
+    use_sac_mode: str | None = None
+    inventory: dict | None = None
+    inventory_updated_at: datetime | None = None
+    created_at: datetime | None = None
+
+
 class HostListResponse(BaseModel):
     items: list[HostSummary]
     total: int
@@ -33,6 +45,7 @@ class EventSummary(BaseModel):
     host_id: int
     hostname: str
     display_name: str | None = None
+    product_version: str | None = None
     occurred_at: datetime
     received_at: datetime
     category: str