- replace globalTree startup loading with globalTopologyGraph
- add topologyGraph adjacency cache with in/out edges, start nodes, and end nodes
- remove multiBranchTreeNode and legacy tree-building helpers
- make topology queries independent of the all-zero UUID virtual root
- keep TOPOLOGY_ANALYSIS on per-task DB querying while clarifying point-to-point reachability results
- add coverage for multi-parent topology reachability
