chore: implement database crud for AI seat usage (#22681)

Creates a new table `ai_seat_state` to keep track of when users consume an ai_seat. Once a user consumes an AI seat, they will forever in this table (as it stands today).

coderd/database/queries.sql.go

@@ -1198,6 +1198,64 @@ func (q *sqlQuerier) UpdateAIBridgeInterceptionEnded(ctx context.Context, arg Up
 	return i, err
 }
 
+const getActiveAISeatCount = `-- name: GetActiveAISeatCount :one
+SELECT
+	COUNT(*)
+FROM
+	ai_seat_state ais
+JOIN
+	users u
+ON
+	ais.user_id = u.id
+WHERE
+	u.status = 'active'::user_status
+	AND u.deleted = false
+	AND u.is_system = false
+`
+
+func (q *sqlQuerier) GetActiveAISeatCount(ctx context.Context) (int64, error) {
+	row := q.db.QueryRowContext(ctx, getActiveAISeatCount)
+	var count int64
+	err := row.Scan(&count)
+	return count, err
+}
+
+const upsertAISeatState = `-- name: UpsertAISeatState :exec
+INSERT INTO ai_seat_state (
+	user_id,
+	first_used_at,
+	last_used_at,
+	last_event_type,
+	last_event_description,
+	updated_at
+)
+VALUES
+	($1, $2, $2, $3, $4, $2)
+ON CONFLICT (user_id) DO UPDATE
+SET
+	last_used_at = EXCLUDED.last_used_at,
+	last_event_type = EXCLUDED.last_event_type,
+	last_event_description = EXCLUDED.last_event_description,
+	updated_at = EXCLUDED.updated_at
+`
+
+type UpsertAISeatStateParams struct {
+	UserID               uuid.UUID         `db:"user_id" json:"user_id"`
+	FirstUsedAt          time.Time         `db:"first_used_at" json:"first_used_at"`
+	LastEventType        AiSeatUsageReason `db:"last_event_type" json:"last_event_type"`
+	LastEventDescription string            `db:"last_event_description" json:"last_event_description"`
+}
+
+func (q *sqlQuerier) UpsertAISeatState(ctx context.Context, arg UpsertAISeatStateParams) error {
+	_, err := q.db.ExecContext(ctx, upsertAISeatState,
+		arg.UserID,
+		arg.FirstUsedAt,
+		arg.LastEventType,
+		arg.LastEventDescription,
+	)
+	return err
+}
+
 const deleteAPIKeyByID = `-- name: DeleteAPIKeyByID :exec
 DELETE FROM
 	api_keys