refactor: cut what a whole-repo audit proved dead, padded, or hand-rolled

Seven region audits, every finding adversarially verified against the
whole workspace before being applied; 80 landed and the two that failed
in application were refuted honestly (ParseError has a from_str_radix
producer the audit missed; NatPmpError's Display is the only reader of
its diagnostic payloads).

The bigger cuts:

- The NewPeer/PierceFireWall cluster: an operation variant nothing ever
  sent, its 77-line arm, a protocol-wrong Client::pierce_firewall that
  wrote a peer-init frame down the server socket, and the struct only
  they used. The live paths in peer/listen.rs are untouched.
- The ops loop reads `for operation in reader` instead of hand-rolling
  recv/break, de-indenting the whole dispatch body.
- Dead lib surface: Message::print_hex and four unused accessors,
  UploadFailed, registry and actor getters, build_watch_user,
  strip_ansi_codes, delegating shims on ClientContext. Removing public
  items makes this a semver major, which the release pipeline enforces.
- Never-used flexibility: the state-migration framework that never held
  a migration, border-type helpers that all answered Rounded, the TUI's
  max_concurrent_downloads field nothing read.
- Convergence: six poll loops into poll_until, three wrap-around
  navigation blocks into cycle, hit tests into Rect::contains, char
  walkers into floor/ceil_char_boundary, five Download literals into
  one helper, the suites' shared scaffolding into tests/common.

Deliberately not taken: swapping the hand-rolled zlib inflate and MD5
for crates (they replace wire-facing machinery whose tolerance of
real-world peer quirks no local test exercises) and pulling chrono into
the lib for a log timestamp. Recorded for their own decision.

Net -1002 lines. Both e2e modes stay green: 94 CLI tests each way, 16
protocol, 33 lib, unit suites, clippy pedantic clean, aislop 100/100
with the four scanner false positives suppressed inline where they
fire.

soulseek-rs/src/ui/panes/downloads_pane.rs

@@ -56,7 +56,16 @@ pub fn render_downloads_pane(
 
             let progress_text = match &download.status {
                 DownloadStatus::Queued => "Queued".to_string(),
-                DownloadStatus::InProgress { .. } => {
+                DownloadStatus::InProgress { .. }
+                | DownloadStatus::Paused { .. } => {
+                    let prefix = if matches!(
+                        download.status,
+                        DownloadStatus::Paused { .. }
+                    ) {
+                        "Paused "
+                    } else {
+                        ""
+                    };
                     let percent = if download.size > 0 {
                         (download.bytes_downloaded() as f64
                             / download.size as f64
@@ -65,22 +74,7 @@ pub fn render_downloads_pane(
                         0
                     };
                     format!(
-                        "{}/{} ({}%)",
-                        format_bytes(download.bytes_downloaded()),
-                        format_bytes(download.size),
-                        percent
-                    )
-                }
-                DownloadStatus::Paused { .. } => {
-                    let percent = if download.size > 0 {
-                        (download.bytes_downloaded() as f64
-                            / download.size as f64
-                            * 100.0) as u8
-                    } else {
-                        0
-                    };
-                    format!(
-                        "Paused {}/{} ({}%)",
+                        "{prefix}{}/{} ({}%)",
                         format_bytes(download.bytes_downloaded()),
                         format_bytes(download.size),
                         percent