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.

README.md

@@ -30,6 +30,10 @@ enthusiasts to share niche music. This repository is that client plus
 
 ## Features
 
+- **Full protocol coverage**: 100% of the modern Soulseek protocol's message
+  set — every code the reference clients do not mark obsolete — implemented in
+  `soulseek-rs-lib` and driven end to end against a real server, not a mock.
+  See the [coverage table](docs/protocol-coverage.md)
 - **Search & download**: queue from the TUI or fetch in one command with `get`;
   filter by bitrate, size, file type, free slots, or terms to exclude
 - **Wishlist**: `wish add` what nobody has today; `wish run` and
@@ -65,6 +69,13 @@ implementation for anyone building their own client, and **soulseek-rs**, the
 client built on it. The library stays lean on dependencies and has none today;
 the client takes them freely.
 
+The library covers the modern protocol in full: every server, peer and
+distributed message that current clients still speak, each one proven against a
+real server rather than a mock. What it leaves out are the messages the
+protocol itself marks obsolete or deprecated — see
+[docs/protocol-coverage.md](docs/protocol-coverage.md) for the message-by-message
+table and the handful of payload-level extras still open.
+
 ### Projects using soulseek-rs-lib
 
 - [seakarr](https://github.com/binhex/seakarr) — automated Soulseek music