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>

plugins/webhook.py

@@ -14,9 +14,15 @@ from derp.plugin import command, event
 log = logging.getLogger(__name__)
 
 _MAX_BODY = 65536  # 64 KB
-_server: asyncio.Server | None = None
-_request_count: int = 0
-_started: float = 0.0
+
+
+def _ps(bot):
+    """Per-bot plugin runtime state."""
+    return bot._pstate.setdefault("webhook", {
+        "server": None,
+        "request_count": 0,
+        "started": 0.0,
+    })
 
 
 def _verify_signature(secret: str, body: bytes, signature: str) -> bool:
@@ -47,7 +53,7 @@ async def _handle_request(reader: asyncio.StreamReader,
                           writer: asyncio.StreamWriter,
                           bot, secret: str) -> None:
     """Parse one HTTP request and dispatch to IRC."""
-    global _request_count
+    ps = _ps(bot)
 
     try:
         # Read request line
@@ -117,7 +123,7 @@ async def _handle_request(reader: asyncio.StreamReader,
         else:
             await bot.send(channel, text)
 
-        _request_count += 1
+        ps["request_count"] += 1
         writer.write(_http_response(200, "OK", "sent"))
         log.info("webhook: relayed to %s (%d bytes)", channel, len(text))
 
@@ -140,9 +146,9 @@ async def _handle_request(reader: asyncio.StreamReader,
 @event("001")
 async def on_connect(bot, message):
     """Start the webhook HTTP server on connect (if enabled)."""
-    global _server, _started, _request_count
+    ps = _ps(bot)
 
-    if _server is not None:
+    if ps["server"] is not None:
         return  # already running
 
     cfg = bot.config.get("webhook", {})
@@ -157,9 +163,9 @@ async def on_connect(bot, message):
         await _handle_request(reader, writer, bot, secret)
 
     try:
-        _server = await asyncio.start_server(handler, host, port)
-        _started = time.monotonic()
-        _request_count = 0
+        ps["server"] = await asyncio.start_server(handler, host, port)
+        ps["started"] = time.monotonic()
+        ps["request_count"] = 0
         log.info("webhook: listening on %s:%d", host, port)
     except OSError as exc:
         log.error("webhook: failed to bind %s:%d: %s", host, port, exc)
@@ -168,18 +174,20 @@ async def on_connect(bot, message):
 @command("webhook", help="Show webhook listener status", admin=True)
 async def cmd_webhook(bot, message):
     """Display webhook server status."""
-    if _server is None:
+    ps = _ps(bot)
+
+    if ps["server"] is None:
         await bot.reply(message, "Webhook: not running")
         return
 
-    socks = _server.sockets
+    socks = ps["server"].sockets
     if socks:
         addr = socks[0].getsockname()
         address = f"{addr[0]}:{addr[1]}"
     else:
         address = "unknown"
 
-    elapsed = int(time.monotonic() - _started)
+    elapsed = int(time.monotonic() - ps["started"])
     hours, rem = divmod(elapsed, 3600)
     minutes, secs = divmod(rem, 60)
     parts = []
@@ -192,5 +200,5 @@ async def cmd_webhook(bot, message):
 
     await bot.reply(
         message,
-        f"Webhook: {address} | {_request_count} requests | up {uptime}",
+        f"Webhook: {address} | {ps['request_count']} requests | up {uptime}",
     )