M1 step 5: IRC App

- Chat: header (Buffer n/N, unread elsewhere, topic or connection
  state), wrapped hh:mm <nick> lines (own in accent, Mentions green,
  info grey), input line; Tab cycles Buffers, Fn+Up/Down scrolls back,
  Enter sends, Back leaves while the IRC Service keeps running
- /settings: server form (host, port, TLS, self-signed pinning, nick,
  SASL, NickServ, auto-join); Save & reconnect restarts the session
- Opening the App starts the IRC Service; viewing a Buffer clears its
  unread count; IrcSession gains a revision counter for redraws

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

lib/irc/src/irc_session.cpp

@@ -62,11 +62,13 @@ int IrcSession::bufferFor(const std::string& name, IrcBuffer::Type type) {
     if (i >= 0) return i;
     if (bufferCount() >= kMaxBuffers) return 0;  // full: fall back to the server Buffer
     buffers_.push_back({name, type, {}, 0, false, false, ""});
+    revision_++;
     return bufferCount() - 1;
 }
 
 void IrcSession::setViewing(int buffer) {
     viewing_ = buffer;
+    revision_++;
     if (buffer >= 0 && buffer < bufferCount()) {
         buffers_[buffer].unread = 0;
         buffers_[buffer].mentioned = false;
@@ -87,6 +89,7 @@ bool IrcSession::mentionsMe(const std::string& text) const {
 void IrcSession::add(int b, IrcLine::Kind kind, const std::string& nick, const std::string& text, int64_t utc,
                      bool mention) {
     IrcBuffer& buf = buffers_[b];
+    revision_++;
     IrcLine line{utc, kind, nick, text};
     buf.lines.push_back(line);
     if (buf.lines.size() > kLinesPerBuffer) buf.lines.pop_front();