Delete Project

Delete a project. With no body it deletes a project that holds nothing, and refuses one that does; `mode` is how you say what should happen to what it holds. **Empty** (no body): the project is removed only while it holds no resources. A project that holds any is refused with 409 `project_not_empty`, and the refusal enumerates what is inside: `error.details.resource_count` is the total, and `error.details.contents` names each kind with a count and up to five names. Every project row also carries that total as `resource_count`, so an application can find the projects it may delete in one list call. Records of work never hold a project open and are not counted. **Detach** (`mode: detach`): only the grouping row is removed; every resource in the project moves to the implicit Default project, where it stays readable and is listed by `?project_id=default`. Refused with 409 `project_has_scoped_credentials` while an API key, service account, vault credential, webhook endpoint, member grant or pending invite is scoped to the project, because detaching any of those would silently widen it. **Purge** (`mode: purge` with `confirm` equal to the project's name): available only on an ARCHIVED project, because a teardown needs a state you can sit in and reverse first; a live project is refused with the coded `409 project_not_archived`. Archive the project, confirm it is the one you mean, then purge. The project is removed WITH its contents in one transaction: the resources it holds and its scoped webhook endpoints and vault credentials are deleted, API keys and service accounts pinned to the project are revoked, and member grants and pending-invite scopes on the project are cleared. Resources with a lifecycle and a delete of their own, such as stores, hosted APIs and files, are not removed: they move to the Default project, and because they do hold a project open, an unqualified delete refuses while any of them is in the project. Refused with 409 while a resource that must be released first is still attached (the refusal names it), while a member's only project grant is this one, or while a live invite carries only this project (clearing either would widen that person to the whole workspace, the invite one acceptance earlier). **A purge is recoverable for 30 days.** The project disappears from every list and read immediately, and its name is freed for reuse, but the project and its resources are kept and permanently deleted only once the window closes. `POST /v1/projects/{project_id}/restore` brings the project and its resources back inside that window; the credentials the purge revoked and the grants it cleared stay that way. The 409 carries the blockers under `error.details.blockers` (`kind`, typed `id`, `name`, and the `blocks` modes each refuses), their total under `error.details.blocker_count`, and, for existing clients, the same rows under `error.details.credentials`. The lists are capped at 50 rows; the counts are not, and the refusal is decided on the count.