The signature check was written out twice — once on the read path, once on
the write path — and a third copy was about to be needed for serving. Three
hand-copies of a verification routine is how a hole gets in, and the
dangerous half is subtle: pubkey recovery always succeeds and always yields
some key, so the line that actually proves anything is the comparison of the
derived address to the on-chain owner. That line is now in one place.
The manifest schema gains a hosts block for per-subdomain records and
routing, validated strictly here because whatever we accept we then serve
under the owner's signature: no path traversal, no non-http redirect
targets, no host key that is not a label path. v1 blobs stay valid, so
nothing anyone has published needs republishing.
Also adds the rule for which hosts entry governs a request. The apex is
deliberately never one of them — its content comes from the chain, and
letting an off-chain blob redirect the main site would move a name's trust
boundary without the owner spending a transaction.
