Permission's zero value is PermissionRead, so Project.MaxPermission serialized
as 0 — a real permission meaning read — on every response path that never
resolved it. GET /api/v1/projects/:project claimed read-only access on a
project you own while the x-max-permission header correctly said 2.
Typing the field *Permission makes that unrepresentable: nil marshals to null,
so "not computed" is the default rather than something each call site has to
remember. That also fixes the paths which serialize a project outside the CRUD
pipeline and had the same lie — the admin project list, the background
handlers, duplicated_project on both API versions, and the admin owner-reassign
route — and retires v2's two explicit resets, which the field type now covers.
Webhook payloads for project.created and project.updated change from 0 to null
along with it.
Fixes#3574
kolaente
dfb469741c