Modelling a relationship which has multiple one-to-many parents
I think your table design is good and normalized.

One thing that is not guaranteed yet is that if a photo references a bedroom, that bedroom should belong to the same house as the photo.

You could get that with an additional UNIQUE constraint:

ALTER TABLE bedroom
   ADD UNIQUE (houseid, bedroomid);


Then the foreign key constraint could be defined as:

ALTER TABLE photo
   ADD FOREIGN KEY (houseid, bedroomid) REFERENCES bedroom (houseid, bedroomid);


An extra index is not nice from a performance angle, but you want an index on the houseid column of bedroom anyway because of the foreign key, so an additional column shouldn't hurt.