feat: add IRC channel support

Add comprehensive IRC over TLS channel implementation with:
- TLS support with optional certificate verification
- SASL PLAIN authentication (IRCv3)
- NickServ IDENTIFY authentication
- Server password support (for bouncers like ZNC)
- Channel and private message (DM) support
- Message splitting for IRC 512-byte line limit
- UTF-8 safe splitting at character boundaries
- Case-insensitive nickname allowlist
- IRC style prefix for LLM responses (plain text only)
- Configurable via TOML or onboard wizard

All 959 tests passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/channels/mod.rs

@@ -2,6 +2,7 @@ pub mod cli;
 pub mod discord;
 pub mod email_channel;
 pub mod imessage;
+pub mod irc;
 pub mod matrix;
 pub mod slack;
 pub mod telegram;
@@ -11,6 +12,7 @@ pub mod whatsapp;
 pub use cli::CliChannel;
 pub use discord::DiscordChannel;
 pub use imessage::IMessageChannel;
+pub use irc::IrcChannel;
 pub use matrix::MatrixChannel;
 pub use slack::SlackChannel;
 pub use telegram::TelegramChannel;
@@ -241,6 +243,7 @@ pub fn handle_command(command: crate::ChannelCommands, config: &Config) -> Resul
                 ("iMessage", config.channels_config.imessage.is_some()),
                 ("Matrix", config.channels_config.matrix.is_some()),
                 ("WhatsApp", config.channels_config.whatsapp.is_some()),
+                ("IRC", config.channels_config.irc.is_some()),
             ] {
                 println!("  {} {name}", if configured { "✅" } else { "❌" });
             }
@@ -347,6 +350,24 @@ pub async fn doctor_channels(config: Config) -> Result<()> {
         ));
     }
 
+    if let Some(ref irc) = config.channels_config.irc {
+        channels.push((
+            "IRC",
+            Arc::new(IrcChannel::new(
+                irc.server.clone(),
+                irc.port,
+                irc.nickname.clone(),
+                irc.username.clone(),
+                irc.channels.clone(),
+                irc.allowed_users.clone(),
+                irc.server_password.clone(),
+                irc.nickserv_password.clone(),
+                irc.sasl_password.clone(),
+                irc.verify_tls.unwrap_or(true),
+            )),
+        ));
+    }
+
     if channels.is_empty() {
         println!("No real-time channels configured. Run `zeroclaw onboard` first.");
         return Ok(());
@@ -514,6 +535,21 @@ pub async fn start_channels(config: Config) -> Result<()> {
         )));
     }
 
+    if let Some(ref irc) = config.channels_config.irc {
+        channels.push(Arc::new(IrcChannel::new(
+            irc.server.clone(),
+            irc.port,
+            irc.nickname.clone(),
+            irc.username.clone(),
+            irc.channels.clone(),
+            irc.allowed_users.clone(),
+            irc.server_password.clone(),
+            irc.nickserv_password.clone(),
+            irc.sasl_password.clone(),
+            irc.verify_tls.unwrap_or(true),
+        )));
+    }
+
     if channels.is_empty() {
         println!("No channels configured. Run `zeroclaw onboard` to set up channels.");
         return Ok(());