[solo applicant] avoid creating a duplicate job row when re-submitting an already-known URL

Proof set for Acquire job (duplicate URL already in workspace)

Pin the G1 "acquire jobs" gestures a solo applicant relies on: pasting a URL must produce a single row anchored on that URL and kick off extract; adding only title+organization must produce a row without an extract description; re-posting a known URL must NOT create a second row (verified via /job-exists + dashboard row count); and the reference L1 story spec proves the end-to-end import-via-API path that feeds straight into the apply suite.