Unify UME World as hex nav with conditional flat world map.

Seed a unique L2 World canvas under the UME World container, show the flat map only when nested regions have NEs, pack blocks without overlap, allow drag overrides on the world map while forbidding direct NE adds, and hide the world-map truncation banner.

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

netx_api/topology_schemas.py

@@ -162,6 +162,7 @@ class TopologyFolderOut(BaseModel):
     name: str
     sort_order: int = 0
     is_system: bool = False
+    external_ref: str = ""
     created_at: datetime | None = None
     updated_at: datetime | None = None
 
@@ -222,6 +223,7 @@ class TopologyTreeFolderOut(BaseModel):
     name: str
     sort_order: int = 0
     is_system: bool = False
+    external_ref: str = ""
     views: list[TopologyTreeViewOut] = Field(default_factory=list)
     children: list["TopologyTreeFolderOut"] = Field(default_factory=list)
 
@@ -276,6 +278,11 @@ class ViewNodeOut(BaseModel):
     device_type: str = ""
     connect_status: str = ""
     managed_source: str = ""  # manual | ume_sync | lldp | topology | webcrt | …
+    # ne | region — region nodes drill into child UME canvases
+    kind: str = "ne"
+    folder_id: str = ""
+    view_id: str = ""
+    node_count: int = 0
 
 
 class ViewEdgeOut(BaseModel):