fix: resolve migrated execution targets for project jobs

[asselstine]

Summary

• resolve deterministic migrated execution-target UUIDs instead of treating them as legacy connection IDs
• preserve project context when creating a job from a project page
• add a regression test for migrated target IDs

Validation

• npm run check --workspace=factorize-app
• npm test --workspace=factorize (PostgreSQL tests skipped: no local PostgreSQL)
• npm test attempted; requires PostgreSQL via npm run bootstrap:test

[linear]

GEN-2362