feat: add multi-server support

Connect to multiple IRC servers concurrently from a single config file.
Plugins are loaded once and shared; per-server state is isolated via
separate SQLite databases and per-bot runtime state (bot._pstate).

- Add build_server_configs() for [servers.*] config layout
- Bot.__init__ gains name parameter, _pstate dict for plugin isolation
- cli.py runs multiple bots via asyncio.gather
- 9 stateful plugins migrated from module-level dicts to _ps(bot) pattern
- Backward compatible: legacy [server] config works unchanged

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

tests/test_webhook.py

@@ -23,6 +23,7 @@ from plugins.webhook import (  # noqa: E402
     _MAX_BODY,
     _handle_request,
     _http_response,
+    _ps,
     _verify_signature,
     cmd_webhook,
     on_connect,
@@ -62,6 +63,7 @@ class _FakeBot:
         self.replied: list[str] = []
         self.actions: list[tuple[str, str]] = []
         self.state = _FakeState()
+        self._pstate: dict = {}
         self._admin = admin
         self.prefix = "!"
         self.config = {
@@ -301,14 +303,14 @@ class TestRequestHandler:
 
     def test_counter_increments(self):
         bot = _FakeBot()
-        # Reset counter
-        _mod._request_count = 0
+        ps = _ps(bot)
+        ps["request_count"] = 0
         body = json.dumps({"channel": "#test", "text": "hi"}).encode()
         raw = _build_request("POST", body, {"Content-Length": str(len(body))})
         reader = _FakeReader(raw)
         writer = _FakeWriter()
         asyncio.run(_handle_request(reader, writer, bot, ""))
-        assert _mod._request_count == 1
+        assert ps["request_count"] == 1
 
 
 # ---------------------------------------------------------------------------
@@ -320,28 +322,23 @@ class TestServerLifecycle:
     def test_disabled_config(self):
         """Server does not start when webhook is disabled."""
         bot = _FakeBot(webhook_cfg={"enabled": False})
-        msg = _msg("", target="")
         msg = Message(raw="", prefix="", nick="", command="001",
                       params=["test", "Welcome"], tags={})
-        # Reset global state
-        _mod._server = None
         asyncio.run(on_connect(bot, msg))
-        assert _mod._server is None
+        assert _ps(bot)["server"] is None
 
     def test_duplicate_guard(self):
         """Second on_connect does not create a second server."""
         sentinel = object()
-        _mod._server = sentinel
         bot = _FakeBot(webhook_cfg={"enabled": True, "port": 0})
+        _ps(bot)["server"] = sentinel
         msg = Message(raw="", prefix="", nick="", command="001",
                       params=["test", "Welcome"], tags={})
         asyncio.run(on_connect(bot, msg))
-        assert _mod._server is sentinel
-        _mod._server = None  # cleanup
+        assert _ps(bot)["server"] is sentinel
 
     def test_on_connect_starts(self):
         """on_connect starts the server when enabled."""
-        _mod._server = None
         bot = _FakeBot(webhook_cfg={
             "enabled": True, "host": "127.0.0.1", "port": 0, "secret": "",
         })
@@ -350,10 +347,10 @@ class TestServerLifecycle:
 
         async def _run():
             await on_connect(bot, msg)
-            assert _mod._server is not None
-            _mod._server.close()
-            await _mod._server.wait_closed()
-            _mod._server = None
+            ps = _ps(bot)
+            assert ps["server"] is not None
+            ps["server"].close()
+            await ps["server"].wait_closed()
 
         asyncio.run(_run())
 
@@ -366,26 +363,25 @@ class TestServerLifecycle:
 class TestWebhookCommand:
     def test_not_running(self):
         bot = _FakeBot()
-        _mod._server = None
         asyncio.run(cmd_webhook(bot, _msg("!webhook")))
         assert any("not running" in r for r in bot.replied)
 
     def test_running_shows_status(self):
         bot = _FakeBot()
-        _mod._request_count = 42
-        _mod._started = time.monotonic() - 90  # 1m 30s ago
+        ps = _ps(bot)
+        ps["request_count"] = 42
+        ps["started"] = time.monotonic() - 90  # 1m 30s ago
 
         async def _run():
             # Start a real server on port 0 to get a valid socket
             srv = await asyncio.start_server(lambda r, w: None,
                                              "127.0.0.1", 0)
-            _mod._server = srv
+            ps["server"] = srv
             try:
                 await cmd_webhook(bot, _msg("!webhook"))
             finally:
                 srv.close()
                 await srv.wait_closed()
-                _mod._server = None
 
         asyncio.run(_run())
         assert len(bot.replied) == 1