The catch-all rule now sends anything that did not match a more specific
rule to furst-serve, while `default` stays a plain browser. Because rules
fall through when their command is missing, that arrangement needs no new
mechanism: if furst-serve is not installed the reader rule is skipped and
the browser still gets the URL.
Firefox drops to a short list of sites that genuinely need it. Every reader
page carries a browser link, so the list can stay short.
Adds a README for furst-serve and rewrites the top-level one around the
whole pipeline: what it is for, what each piece does, measured output
sizes, and the limits — client-rendered pages, rate-limited search
endpoints, DRM.
