Panel 2 — the network graph drawn in the bloccs hexagon notation. The layout
is computed server-side (Bloccs.Web.Topology.Layout) and rendered as a single
SVG: one <.hex_glyph> per node, one cubic-bezier <path> per edge. Live node
state (states[node_id]) is an assign-driven CSS class on each glyph — no
client animation. P4 feeds states; in P3 every node is :idle.