feat: initial implementation

Asyncio IRC bot with decorator-based plugin system.
Zero external dependencies, Python 3.11+.

- IRC protocol: message parsing, formatting, async TCP/TLS connection
- Plugin system: @command and @event decorators, file-based loading
- Bot orchestrator: connect, dispatch, reconnect, nick recovery
- CLI: argparse entry point with TOML config
- Built-in plugins: ping, help, version, echo
- 28 unit tests for parser and plugin system

config/derp.toml

@@ -0,0 +1,16 @@
+[server]
+host = "irc.libera.chat"
+port = 6697
+tls = true
+nick = "derp"
+user = "derp"
+realname = "derp IRC bot"
+password = ""
+
+[bot]
+prefix = "!"
+channels = ["#test"]
+plugins_dir = "plugins"
+
+[logging]
+level = "info"