feat: implement server logging functionality

- Added a logging service to manage server event logs including message edits, deletions, member joins/leaves, and moderation actions.
- Introduced commands to configure logging settings, including setting the log channel and enabling/disabling logging.
- Updated the README to document the new logging features and commands.
- Enhanced moderation commands to log actions taken on members.

internal/db/repos/settingsrepo/repo.go

@@ -15,6 +15,12 @@ type LevelReward struct {
 	RoleID  int64
 }
 
+type LogSettings struct {
+	GuildID   int64
+	ChannelID int64
+	IsEnabled bool
+}
+
 func NewRepo(db *sql.DB) *Repo {
 	return &Repo{db: db}
 }
@@ -240,6 +246,80 @@ func (r *Repo) SetLevelUpMessage(ctx context.Context, guildID int64, message str
 	return err
 }
 
+func (r *Repo) SetLogChannel(ctx context.Context, guildID int64, channelID int64) error {
+	const q = `
+		INSERT INTO logsettings (guild_id, log_channel_id, is_enabled)
+		VALUES ($1, $2, TRUE)
+		ON CONFLICT (guild_id)
+		DO UPDATE SET log_channel_id = EXCLUDED.log_channel_id
+	`
+	_, err := r.db.ExecContext(ctx, q, guildID, channelID)
+	return err
+}
+
+func (r *Repo) SetLogEnabled(ctx context.Context, guildID int64, enabled bool) error {
+	const q = `
+		INSERT INTO logsettings (guild_id, is_enabled)
+		VALUES ($1, $2)
+		ON CONFLICT (guild_id)
+		DO UPDATE SET is_enabled = EXCLUDED.is_enabled
+	`
+	_, err := r.db.ExecContext(ctx, q, guildID, enabled)
+	return err
+}
+
+func (r *Repo) GetLogSettings(ctx context.Context, guildID int64) (*LogSettings, error) {
+	const q = `
+		SELECT log_channel_id, is_enabled
+		FROM logsettings
+		WHERE guild_id = $1
+	`
+	row := r.db.QueryRowContext(ctx, q, guildID)
+	var channelID sql.NullInt64
+	var enabled sql.NullBool
+	switch err := row.Scan(&channelID, &enabled); err {
+	case nil:
+		out := &LogSettings{
+			GuildID:   guildID,
+			ChannelID: 0,
+			IsEnabled: false,
+		}
+		if channelID.Valid {
+			out.ChannelID = channelID.Int64
+		}
+		if enabled.Valid {
+			out.IsEnabled = enabled.Bool
+		}
+		return out, nil
+	case sql.ErrNoRows:
+		return &LogSettings{
+			GuildID:   guildID,
+			ChannelID: 0,
+			IsEnabled: false,
+		}, nil
+	default:
+		return nil, err
+	}
+}
+
+func (r *Repo) HasLogSettings(ctx context.Context, guildID int64) (bool, error) {
+	const q = `
+		SELECT 1
+		FROM logsettings
+		WHERE guild_id = $1
+	`
+	row := r.db.QueryRowContext(ctx, q, guildID)
+	var one int
+	switch err := row.Scan(&one); err {
+	case nil:
+		return true, nil
+	case sql.ErrNoRows:
+		return false, nil
+	default:
+		return false, err
+	}
+}
+
 func (r *Repo) GetLevelUpMessage(ctx context.Context, guildID int64) (string, error) {
 	const q = `
 		SELECT message