IRC App: Alt scrolls, Up/Down recall sent lines; /j for /join

- Alt + ; / Alt + . scroll the Buffer back and forward
- Up / Down (Fn + ; / Fn + .) browse the last 30 sent lines, shell-style,
  returning to the draft past the newest (InputHistory, host-tested)
- /j is short for /join

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

lib/irc/src/irc_session.cpp

@@ -326,7 +326,7 @@ void IrcSession::command(int b, const std::string& text, int64_t utc) {
     const IrcBuffer& buf = buffers_[b];
     bool inChannel = buf.type == IrcBuffer::Type::Channel;
 
-    if (verb == "join") {
+    if (verb == "join" || verb == "j") {
         auto [channel, key] = firstWord(rest);
         if (channel.empty()) return info(b, "Usage: /join #channel", utc);
         if (!isChannel(channel)) channel = "#" + channel;
@@ -362,7 +362,7 @@ void IrcSession::command(int b, const std::string& text, int64_t utc) {
     } else if (verb == "raw" || verb == "quote") {
         if (!rest.empty()) send(rest);
     } else {
-        info(b, "Unknown command /" + verb + " (try /join /part /msg /me /nick /topic /names /quit /raw)", utc);
+        info(b, "Unknown command /" + verb + " (try /join or /j, /part /msg /me /nick /topic /names /quit /raw)", utc);
     }
 }