fix: protect server config from truncation and recover from Discord guilds

- Save servers_config.json atomically via temp file + fsync + rename
- Keep .bak backup and auto-restore when main config is empty/corrupt
- Add /servers/recover endpoint for manual recovery
- Auto-recover basic server configs on startup when config is empty but bot is in guilds

bot/bot.py

@@ -163,6 +163,42 @@ async def on_ready():
     # Start server-specific schedulers (includes DM mood rotation)
     server_manager.start_all_schedulers(globals.client)
     
+    # Auto-recover server config if it was lost/corrupted (e.g., disk full)
+    if not server_manager.servers and globals.client.guilds:
+        logger.warning("⚠️ Server config is empty but bot is in guilds — attempting auto-recovery")
+        recovered = 0
+        for guild in globals.client.guilds:
+            text_channels = [ch for ch in guild.text_channels if ch.permissions_for(guild.me).send_messages]
+            if not text_channels:
+                text_channels = guild.text_channels
+            if not text_channels:
+                continue
+            preferred = None
+            for ch in text_channels:
+                if ch.name.lower() in ("general", "chat", "main", "lounge", "general-chat"):
+                    preferred = ch
+                    break
+            channel = preferred or text_channels[0]
+            try:
+                server_manager.add_server(
+                    guild_id=guild.id,
+                    guild_name=guild.name,
+                    autonomous_channel_id=channel.id,
+                    autonomous_channel_name=f"#{channel.name}",
+                    bedtime_channel_ids=[channel.id],
+                    enabled_features={"autonomous", "bedtime", "monday_video"}
+                )
+                recovered += 1
+                logger.info(f"🔄 Auto-recovered server: {guild.name} (ID: {guild.id}) → #{channel.name}")
+            except Exception as e:
+                logger.error(f"Failed to auto-recover server {guild.name}: {e}")
+        if recovered > 0:
+            logger.info(f"✅ Auto-recovered {recovered} server(s) — restarting schedulers")
+            server_manager.stop_all_schedulers()
+            server_manager.start_all_schedulers(globals.client)
+        else:
+            logger.warning("Auto-recovery found no recoverable servers")
+    
     # Start the global scheduler for other tasks
     globals.scheduler.start()