Start Twitch alerts and tickets off on new servers

Every module that can be switched on or off now starts off. A server
with no settings yet reads as off; setting the Twitch alert channel or
running /tickets setup for the first time turns that module on, and
existing settings are left as they are. schema.sql mirrors the API's
migration 000019.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

internal/db/repos/twitchrepo/repo.go

@@ -102,10 +102,13 @@ func (r *Repo) GetNotificationChannel(ctx context.Context, guildID int64) (int64
 	return chID.Int64, true, nil
 }
 
+// SetNotificationChannel sets where live alerts go. Setting it for the first
+// time turns alerts on (they start off); after that, the on/off switch is
+// left alone.
 func (r *Repo) SetNotificationChannel(ctx context.Context, guildID, channelID int64) error {
 	const q = `
-		INSERT INTO twitch_config (guild_id, twitch_channel_id)
-		VALUES ($1, $2)
+		INSERT INTO twitch_config (guild_id, twitch_channel_id, enabled)
+		VALUES ($1, $2, TRUE)
 		ON CONFLICT (guild_id)
 		DO UPDATE SET twitch_channel_id = EXCLUDED.twitch_channel_id
 	`
@@ -114,15 +117,14 @@ func (r *Repo) SetNotificationChannel(ctx context.Context, guildID, channelID in
 }
 
 // IsEnabled reports whether Twitch notifications are enabled for guildID.
-// A guild with no twitch_config row yet defaults to enabled, matching the
-// column's own DEFAULT TRUE - "never configured" and "explicitly on" are
-// the same state until someone actually flips it off.
+// A guild with no twitch_config row yet is off: modules start off until
+// the server sets them up.
 func (r *Repo) IsEnabled(ctx context.Context, guildID int64) (bool, error) {
 	const q = `SELECT enabled FROM twitch_config WHERE guild_id = $1`
 	var enabled bool
 	err := r.db.QueryRowContext(ctx, q, guildID).Scan(&enabled)
 	if err == sql.ErrNoRows {
-		return true, nil
+		return false, nil
 	}
 	if err != nil {
 		return false, err