feat: add Docker support and bot configuration

- Introduced Dockerfile for building the bot application using Go.
- Added .dockerignore to exclude unnecessary files from the Docker context.
- Updated docker-compose.yml to define the bot service and its dependencies, including environment variables for database and Lavalink configuration.
- Modified internal configuration to streamline environment variable handling.

internal/config/config.go

@@ -8,12 +8,12 @@ import (
 )
 
 type Config struct {
-	BotToken      string
-	AppID         string
-	GuildID       string
-	DBHost        string
-	LavalinkHost  string
-	LavalinkPass  string
+	BotToken       string
+	AppID          string
+	GuildID        string
+	DBHost         string
+	LavalinkHost   string
+	LavalinkPass   string
 	TwitchClientID string
 }
 
@@ -33,9 +33,6 @@ func LoadConfig() (*Config, error) {
 	}
 
 	guildID := os.Getenv("GUILD_ID")
-	if guildID == "" {
-		return nil, fmt.Errorf("GUILD_ID is not set")
-	}
 
 	dbHost := os.Getenv("DB_HOST")
 	if dbHost == "" {