feat: integrate music commands with Lavalink support

- Added new music commands: play, queue, and volume.
- Implemented music management using disgolink for Lavalink integration.
- Updated bot initialization to include Lavalink host and password.
- Enhanced interaction handling for music commands, requiring DJ role for usage.
- Introduced now playing message with interactive buttons for controlling playback.
- Updated dependencies in go.mod for disgolink and snowflake.

internal/commands/music/public/volume.go

@@ -0,0 +1,63 @@
+package public
+
+import (
+	"fmt"
+	"velox-bot/internal/music"
+
+	"github.com/bwmarrin/discordgo"
+)
+
+var Volume = &discordgo.ApplicationCommand{
+	Name:        "volume",
+	Description: "Set playback volume (0-150)",
+	Options: []*discordgo.ApplicationCommandOption{
+		{
+			Type:        discordgo.ApplicationCommandOptionInteger,
+			Name:        "value",
+			Description: "Volume percent (0-150)",
+			Required:    true,
+			MinValue:    ptrFloat(0),
+			MaxValue:    150,
+		},
+	},
+}
+
+func VolumeHandler(s *discordgo.Session, i *discordgo.InteractionCreate) {
+	_ = s.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
+		Type: discordgo.InteractionResponseDeferredChannelMessageWithSource,
+		Data: &discordgo.InteractionResponseData{
+			Content: "Updating volume...",
+			Flags:   discordgo.MessageFlagsEphemeral,
+		},
+	})
+
+	if !memberHasDJRole(s, i.GuildID, i.Member) {
+		_, _ = s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{
+			Content: ptr("You need the **DJ** role to use music commands."),
+		})
+		return
+	}
+
+	data := i.ApplicationCommandData()
+	if len(data.Options) == 0 {
+		_, _ = s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{
+			Content: ptr("Missing volume value."),
+		})
+		return
+	}
+
+	vol := int(data.Options[0].IntValue())
+	if err := music.SetVolume(i.GuildID, vol); err != nil {
+		_, _ = s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{
+			Content: ptr(fmt.Sprintf("Error: %v", err)),
+		})
+		return
+	}
+
+	_, _ = s.InteractionResponseEdit(i.Interaction, &discordgo.WebhookEdit{
+		Content: ptr(fmt.Sprintf("Volume set to **%d%%**.", vol)),
+	})
+}
+
+func ptrFloat(v float64) *float64 { return &v }
+