Remove yalc

[alexeyr-ci2]

Now that we use Yarn workspaces for RORP packages, we can also use them for the dummy apps and remove Yalc. This will simplify scripts, CI, and make the repo more understandable for both developers and LLMs.

This task should only be done after the full monorepo merger plan is completed, to avoid interfering with it.

[justin808]

Related: #2120 proposes migrating to pnpm after yalc is removed. The pnpm migration can be done in parallel with or after the yalc removal, as pnpm's workspace linking would replace yalc entirely.