* docs: bring doc titles and descriptions into SEO length limits
Rewrite the frontmatter title and description of every published doc so the
rendered <title> lands in 50-60 characters (including the site suffix) and the
meta description lands in 150-160 characters.
* docs: move SEO titles to a seoTitle field and restore display titles
The frontmatter title renders as the page H1 and the sidebar label, so tuning it
for the title tag shortened nothing and lengthened the visible navigation. Put
the search-facing string in seoTitle and give title back its original value.
The port tables were wrong in both directions: inter-node traffic is QUIC over
UDP rather than TCP, and the shard range 9991-9993 no longer exists. Ports are
unique within a host rather than across the cluster, so every machine uses the
same three, and a single-node install opens only the S3 port because colocated
nodes talk over an in-process pipe.
The reference architectures scripted a move of node data out of a directory
layout that no longer exists, which would have broken any install following
them. The update guide now says object storage has no migration path.