Create a candidate in CATS ATS and add them to a job's pipeline via the API

Steps

1. Generate a v3 API key from CATS Administration settings, then authenticate every request with an 'Authorization: Token <Your API Key>' header against host https://api.catsone.com/v3 (JSON only).
2. Create a candidate with POST /candidates; add ?check_duplicate=true to avoid creating a second record for someone who already exists. Emails go in as an array of {email, is_primary} objects, phones as {number, extension, type} objects, and custom fields as {id, value} pairs.
3. Look up an existing candidate with GET /candidates/{id}, or list/page through candidates with GET /candidates?page=&per_page=.
4. Add the candidate to a job's pipeline: CATS models this as its own pipelines resource — POST /pipelines associates a candidate with a job and returns a new pipeline id representing where they sit in that job's hiring stages.
5. Move the candidate through stages by updating that pipeline's status; CATS fires a pipeline.status_changed webhook carrying pipeline_id, previous_status_id, and new_status_id whenever this happens.
6. Watch the API-wide rate limit: 500 requests/hour, with rate-limit info returned in response headers and a 429 Too Many Requests if you exceed it.