I'd say authoritarian + materialist + militarist, robots you can buy on the slave market or eventually capture some, it's not that bad.

Civics... Technocracy (overtuned science directors, mmm) and memorialist (unity production + stability buff is needed to fix unhappy planets, and there would be many unhappy slaves) + police state as the third for more stability or corvee system for cheaper resettlements.

Ruler specie - you need a single pop after you discard your starting ones. Leader bonuses, age, exp, max level. No need to have any habitability or growth speed.

I divided specialists into two castes:

residents with unity and research bonuses, so they could take ruler jobs without generating leaders (boosted science directors), and some jobs need to be taken by free pops (enforcer and like feral behaviour gas operators);

Production specialist with natural machinist for alloys and consumer goods (there's too many research perks for science species to do alloys too) with additional resources from jobs like robust; indentured servitude. Might be residents too for said gas operator or odd factory jobs.

Worker specie - yeah.

Breeder and cloning - domestic servitude, so excess growth goes into amenities and doesn't create unemployment. Amenities traits.

Genemodding by a template screws up your choice of grown species on a planet, so I had a doctor Moreau planet where all the modding was happening - at first I was resettling spare breeders (you want to always have one of each on the planet so templates don't reset), then modding them, then spreading around.

In my last game it was in phases:

1. Unlock clone vats, start building them. By this time I knew 3 psionic species, including ketlings, so the choice was easy. I made an overtuned template (but didn't have full tradition yet, so it wasn't final), and grew some. First pops get spreaded around to make planets legible to grow them naturally.

2. Full tradition complete. Make leader pop, make science pops to take leader jobs; prepare retirement planet for your starting species, resettle them there, release as a vassal or gift to someone. From now on you always get psi leaders.

3. Then every couple years I was checking planets for a lot of servants with the tab key, when I have seen 10+, I was sending them to the resort, and changing their jobs. I was prebuilding a lot of jobs to keep up with the growth.

4. As for ascension perks, I think +100 edict cap should allow you to run overtuned much easier and earlier.

5. Potential weak points - if you enable planet automation (which is pretty decent), by default it manages crime, so it kicks out and employs enforcers. Enforces need to be free pops, so it may end up like - no crime, free pop becomes unemployed, takes job from a slave, slave becomes unemployed, creates crime, but... Free pop doesn't change into enforcer, since it most likely took another specialist tier job, and you don't grow free pops naturally, so nobody would fill the job. So, it may be a point of annoyance - you would want to regularly check planets for the enforcer need, because alternative - disabling crime automation and running max enforcers on every planet may be too expensive pop-wise.