Can you continue to work in the UK indefinitely with settled status without applying for citizenship?
Yes. Settled status is a form of Indefinite Leave to Remain (ILR).
The difference is what happens if you leave the UK for an extended period. If you have settled status, but later decide to work in another country, you will lose your settled status if you are abroad for 5 years without returning to the UK. (See also this FAQ on settled status 5-year absences)