feat(bots): bot framework polish + store

- /ws/bot endpoint: bot token auth via query param, SHA-256 lookup
- Bot WS actions: SEND_MESSAGE + DELETE_MESSAGE handled in gateway
- Bot messages: bot_id on messages table, bot badge in chat (green + BOT tag)
- Bot store: /bots lists all bots with server count + add-to-server
- Bot manager moved to /bots/manage
- Fix: command routes were double-nested under /bots/{botID}/commands
- Fix: fetchServerCommands route corrected to /bots/servers/...

internal/gateway/events.go

@@ -23,6 +23,10 @@ const (
 	EventVoiceMute      = "VOICE_MUTE"
 	EventVoiceDeafen    = "VOICE_DEAFEN"
 	EventVoiceWhisper   = "VOICE_WHISPER"
+
+	// Bot action events (sent by bot clients)
+	BotSendMessage    = "SEND_MESSAGE"
+	BotDeleteMessage  = "DELETE_MESSAGE"
 )
 
 // Event represents a WebSocket event sent to clients.