The landing kept expanding whenever documentation was added inline. Moving it
to its own subdirectory gives docs room to grow and keeps the landing to the
"try it / roadmap / verify" story it's supposed to be.
* docs/index.html — TOC + eight sections (TLD registry, registration,
records, resolver, mainnet pricing, tracker, verification, runbook).
Reads on its own; no dependency on the landing.
* index.html — #docs section shrunk to a one-paragraph call-to-action with a
prominent "Open the docs →" button; nav Docs link now points at /docs/.
* portal.html + theseus/index.html — nav Docs links updated to /docs/ (was
./#docs / ../#docs) so every subpage points at the standalone docs.
