A conventional note graph would be almost empty here — the vault has very few note-to-note links. So this maps what actually connects: tags that keep appearing together. Bigger circle, more notes. Thicker line, more overlap.
Adjacency comes from tagPairs in /api/notes.json, computed at build
time from the inline #tags in each note. Nothing was authored to make this work,
which is exactly why it also doubles as a diagnostic: sparse areas here are sparse in
the vault.