IRC: join after NickServ login, keyed auto-join, SASL fallback

- With NickServ, auto-join waits for the logged-in reply (900) or 2 s
  at most, so registered-only IRC channels let us in
- A failed SASL login falls back to NickServ (its own password, or the
  SASL account and password)
- IDENTIFY names the account explicitly, and once logged in on a
  fallback nick, REGAIN takes ours back from a stale session
- Auto-join entries take keys ("#private key, #public"); keys from
  /join are reused when rejoining; keyed channels go first in JOIN
- Serial irc dump: whole Buffers, and which login is configured
  (never the secrets)

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

lib/irc/src/irc_config.cpp

@@ -36,7 +36,8 @@ std::string IrcConfig::validate() const {
     if (port < 1 || port > 65535) return "Port must be 1 to 65535";
     if (!validNick(nick)) return "Nick: letters, digits and []\\`_^{|}- only, not starting with a digit";
     for (auto& c : autojoin)
-        if (c.size() < 2 || (c[0] != '#' && c[0] != '&')) return "IRC channels start with # or &";
+        if (c.channel.size() < 2 || (c.channel[0] != '#' && c.channel[0] != '&'))
+            return "Auto-join: IRC channels start with # or &, each followed by its key if it has one";
     return "";
 }
 
@@ -56,23 +57,27 @@ std::string IrcConfig::save() {
     return "";
 }
 
-std::vector<std::string> IrcConfig::parseChannels(const std::string& text) {
-    std::vector<std::string> out;
-    std::string current;
-    for (char c : text + " ") {
-        if (c == ' ' || c == ',') {
-            if (!current.empty()) out.push_back(current);
-            current.clear();
-        } else {
-            current += c;
-        }
+std::vector<IrcChannel> IrcConfig::parseChannels(const std::string& text) {
+    std::vector<IrcChannel> out;
+    std::string word;
+    auto take = [&]() {
+        if (word.empty()) return;
+        bool channel = word[0] == '#' || word[0] == '&';
+        if (!channel && !out.empty() && out.back().key.empty()) out.back().key = word;
+        else out.push_back({word, ""});  // a stray word fails validation as a channel
+        word.clear();
+    };
+    for (char c : text) {
+        if (c == ' ' || c == ',') take();
+        else word += c;
     }
+    take();
     return out;
 }
 
-std::string IrcConfig::formatChannels(const std::vector<std::string>& channels) {
+std::string IrcConfig::formatChannels(const std::vector<IrcChannel>& channels) {
     std::string out;
-    for (auto& c : channels) out += (out.empty() ? "" : " ") + c;
+    for (auto& c : channels) out += (out.empty() ? "" : ", ") + c.channel + (c.key.empty() ? "" : " " + c.key);
     return out;
 }