Optimize topology canvas per the 2026-10-12 plan.

Save path: one atomic POST /views/{id}/commit (edges, ports, styles, node
add/remove, positions) replaces the multi-request save. Edge styles and
manual-edge port edits now go through dirty/undo/save instead of writing
immediately; non-manual edge ports are read-only.

Data safety: UI saves no longer clear MCP node locks or freeze the device
name into the placement label (label_override + omit-means-keep semantics,
also applied to the MCP positions tool). Adding NEs/neighbors with unsaved
edits now saves first instead of silently dropping them. Positions no longer
bypass membership caps, except persisting synthesized child-region icons.

Fixes found in acceptance: nodes added in the same commit kept (40,40)
under autoflush=False; edits on edges deleted in the same save 404'd the
whole save; box-selection drags and arrow-key moves were not marked dirty;
large canvases far from the origin opened blank and locate did nothing
because fitView waits for measurement that onlyRenderVisibleElements never
does (now fitBounds from known geometry).

Also: batch N+1 lookups in graph/positions, deterministic truncation,
outside-peer scan excludes internal edges, split TopologyPage into hooks,
fix flaky UME/LLDP port test, add scripts/topology_clear_frozen_labels.py.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_ume_topology_apply.py

@@ -345,20 +345,12 @@ class UmeFabricApplyTests(unittest.TestCase):
         edge.source = "ume"
         edge.attrs = {"sources": ["ume"], "ume_link_id": "link-1"}
         self.db.commit()
-        a = (
-            self.db.query(TopoFabricNode)
-            .filter(TopoFabricNode.ume_ne_id == "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa")
-            .one()
-        )
-        b = (
-            self.db.query(TopoFabricNode)
-            .filter(TopoFabricNode.ume_ne_id == "bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb")
-            .one()
-        )
+        # Ports are already assigned to the edge's canonical A/B order; pass the
+        # same node ids so _normalize_endpoints cannot swap ports onto the wrong ends.
         edge2, action = upsert_fabric_edge(
             self.db,
-            a_node_id=a.id,
-            b_node_id=b.id,
+            a_node_id=edge.a_node_id,
+            b_node_id=edge.b_node_id,
             a_port=rich_a,
             b_port=rich_b,
             source="lldp",