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

src/apps/irc_app.cpp

@@ -294,7 +294,7 @@ void IrcApp::drawSettings(Canvas& c) {
         c.setTextColor(theme::kMuted);
         c.drawString(fieldLabel(fields_.selected()).c_str(), 4, area.y + 4);
         widgets::lineEditor(c, fieldEditor_, {4, area.y + 22, area.w - 8, 0});
-        c.drawString(fields_.selected() == kAutojoin ? "e.g. #roro #meshtastic" : "Enter: OK   `: cancel", 4,
+        c.drawString(fields_.selected() == kAutojoin ? "e.g. #roro, #private key" : "Enter: OK   `: cancel", 4,
                      area.y + 44);
         return;
     }