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_session.h

@@ -2,6 +2,7 @@
 
 #include <cstdint>
 #include <deque>
+#include <map>
 #include <set>
 #include <string>
 #include <vector>
@@ -53,6 +54,12 @@ class IrcSession {
 
     explicit IrcSession(const IrcConfig& config);
 
+    // Joins wait this long for NickServ to confirm a login before going ahead anyway.
+    static constexpr uint32_t kNickservWaitMs = 2000;
+
+    // Uptime in ms, called regularly: releases joins held back for NickServ.
+    void tick(uint32_t nowMs);
+
     void connected(int64_t utc);
     void disconnected(int64_t utc, const std::string& reason);
     void receive(const std::string& raw, int64_t utc);
@@ -83,6 +90,7 @@ class IrcSession {
     bool mentionsMe(const std::string& text) const;
     void onPrivmsg(const IrcMessage& m, int64_t utc, bool notice);
     void onWelcome(const IrcMessage& m, int64_t utc);
+    void joinChannels();
     void command(int buffer, const std::string& text, int64_t utc);
     void say(int buffer, const std::string& text, int64_t utc, bool action);
 
@@ -94,6 +102,11 @@ class IrcSession {
     int viewing_ = -1;
     std::set<std::string> namesRequested_;
     std::vector<std::string> rejoin_;  // IRC channels to join again after a reconnect
+    std::map<std::string, std::string> keys_;  // lower-case IRC channel -> key, from config and /join
+    bool joinsHeld_ = false;            // waiting for NickServ before joining
+    bool saslFailed_ = false;
+    uint32_t heldSinceMs_ = 0;
+    uint32_t nowMs_ = 0;
     IrcEffects effects_;
     uint32_t revision_ = 0;
 };