fix(coord-tui): drop "coord-tui [" prefix — title = peer_id exactly

Window title now matches the peer_id column in the TUI 1:1 so users
running multiple windows can map titles to table rows without parsing
a prefix.  Pairs with the coord-hooks.sh change that does the same for
shell-launched claude/gemini/cursor/codex windows and adds the new
BOJ_SUPERVISOR=1 env-var hook for a distinct supervisor background.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

coord-tui/src/main.rs

@@ -174,7 +174,8 @@ impl App {
                 self.token   = v["token"].as_str().map(String::from);
                 let id = self.peer_id.as_deref().unwrap_or("?");
                 self.msg = format!("registered as {}", id);
-                let _ = execute!(std::io::stdout(), SetTitle(format!("coord-tui [{}]", id)));
+                // Title = peer_id exactly so it 1:1-matches the table column.
+                let _ = execute!(std::io::stdout(), SetTitle(id.to_string()));
                 self.refresh();
             }
             Ok(v) => self.msg = format!("register failed: {}", str_field(&v, "error")),