Adds a per-section table of contents at the top of the doc, wrapped
in <details> so it's collapsed by default (the spec body is visible
as soon as the file opens; click "Contents" to navigate). Every H2
and H3 heading is linked, including the unnumbered §14 failure-mode
categories.
Also wraps §11.6 (NomadNet specifics) in <details> — it's already
flagged "informational, not normative" and is the longest H3 sub-tree
in the document. Readers implementing only the §11 wire layer can
skim past it; readers implementing a NomadNet client one click away.
tools/_gen_toc.py regenerates the ToC by re-extracting headings.
Run it after adding/removing/renaming any H2 or H3.
Picked this over the per-layer-file split previously listed in todo
because the split would have broken ~37 cross-references (flow docs,
verifier docstrings, agent.md, README) for marginal reader benefit
at the document's current size (~3300 lines).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
