v1.5.5

v1.5.5 — Learned weighted-graph topology substrate

Connection strengths that recall reinforces and maintenance decays.

Added

• Topology substrate — shared, decayable weighted graph (Topology,
  Edge, NodeId, node_id_for) with serde-backed TopologyStore.

Changed

• Recall learns connections — co-surfaced records reinforce their edge.
• Maintenance ages the topology — un-reinforced edges decay (use-it-or-lose-it).
• Causal discovery reads learned weights — prefers learned topology over
  static Record.connections. Opt-in; public API unchanged.