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/cron.py

@@ -18,10 +18,15 @@ _MIN_INTERVAL = 60
 _MAX_INTERVAL = 604800  # 7 days
 _MAX_JOBS = 20
 
-# -- Module-level tracking ---------------------------------------------------
+# -- Per-bot plugin runtime state --------------------------------------------
 
-_jobs: dict[str, dict] = {}
-_tasks: dict[str, asyncio.Task] = {}
+
+def _ps(bot):
+    """Per-bot plugin runtime state."""
+    return bot._pstate.setdefault("cron", {
+        "jobs": {},
+        "tasks": {},
+    })
 
 
 # -- Pure helpers ------------------------------------------------------------
@@ -101,7 +106,7 @@ async def _cron_loop(bot, key: str) -> None:
     """Repeating loop: sleep, then dispatch the stored command."""
     try:
         while True:
-            data = _jobs.get(key)
+            data = _ps(bot)["jobs"].get(key)
             if not data:
                 return
             await asyncio.sleep(data["interval"])
@@ -118,33 +123,36 @@ async def _cron_loop(bot, key: str) -> None:
 
 def _start_job(bot, key: str) -> None:
     """Create and track a cron task."""
-    existing = _tasks.get(key)
+    ps = _ps(bot)
+    existing = ps["tasks"].get(key)
     if existing and not existing.done():
         return
     task = asyncio.create_task(_cron_loop(bot, key))
-    _tasks[key] = task
+    ps["tasks"][key] = task
 
 
-def _stop_job(key: str) -> None:
+def _stop_job(bot, key: str) -> None:
     """Cancel and remove a cron task."""
-    task = _tasks.pop(key, None)
+    ps = _ps(bot)
+    task = ps["tasks"].pop(key, None)
     if task and not task.done():
         task.cancel()
-    _jobs.pop(key, None)
+    ps["jobs"].pop(key, None)
 
 
 # -- Restore on connect -----------------------------------------------------
 
 def _restore(bot) -> None:
     """Rebuild cron tasks from persisted state."""
+    ps = _ps(bot)
     for key in bot.state.keys("cron"):
-        existing = _tasks.get(key)
+        existing = ps["tasks"].get(key)
         if existing and not existing.done():
             continue
         data = _load(bot, key)
         if data is None:
             continue
-        _jobs[key] = data
+        ps["jobs"][key] = data
         _start_job(bot, key)
 
 
@@ -211,7 +219,7 @@ async def cmd_cron(bot, message):
         if not found_key:
             await bot.reply(message, f"No cron job #{cron_id}")
             return
-        _stop_job(found_key)
+        _stop_job(bot, found_key)
         _delete(bot, found_key)
         await bot.reply(message, f"Removed cron #{cron_id}")
         return
@@ -275,7 +283,7 @@ async def cmd_cron(bot, message):
             "added_by": message.nick,
         }
         _save(bot, key, data)
-        _jobs[key] = data
+        _ps(bot)["jobs"][key] = data
         _start_job(bot, key)
 
         fmt_interval = _format_duration(interval)