docs: lead with the protocol coverage, and drop a stale upload assertion

The message-set coverage is the crate's strongest claim, so say it where
people look first: the README features list and About, the website home
and community pages, each pointing at the coverage table. The table now
carries a section naming what the message set does not reach, so the
claim has something behind it rather than standing on its own.

The upload streaming test still asserted the uploader was blocked
waiting for the downloader's close — the wait that came out when it
started costing the upload slot. It passed only while the thread had yet
to be scheduled, and failed whenever it had.

website/src/pages/community.tsx

@@ -269,8 +269,10 @@ export const Community = () => {
           eyebrow="built on the library"
           title="Projects using soulseek-rs-lib."
         >
-          The protocol crate is there for anyone building their own client or
-          automation on Soulseek. These projects do.
+          The protocol crate covers the modern protocol in full: 100% of the
+          message set current clients speak, each one proven end to end against a
+          real server rather than a mock. It is there for anyone building their
+          own client or automation on Soulseek — these projects do.
         </SectionHead>
         <Cols start>
           <Prose>

website/src/pages/home.tsx

@@ -227,7 +227,8 @@ const About = () => (
         <Callout title="build your own">
           <p>
             Reach for <Code>soulseek-rs-lib</Code> to build a custom client or an agent on
-            the protocol.{' '}
+            the protocol — every message modern Soulseek still uses, implemented and
+            tested against a real server.{' '}
             <Link to="/install" className="text-link hover:text-link-hover">
               Use the library
             </Link>