Enforce the permission-name rule at discovery, for every plugin

todo.md

@@ -2,6 +2,7 @@
 
 ## Unfinnished work
 
+- [ ] (Three decisions inherited from the 2026-08-05 architecture review, to settle inside the next item rather than re-derive: (1) `permissions:write` should mean "may grant a permission to anyone", not "may use the Permissions screen" — so the lockout guard relocates to Users/Groups instead of dying with the screen. (2) The `<resource>:<action>` rule is now enforced at discovery, so deleting the screen no longer removes its enforcement — but the *create form* goes, so minting moves to whatever the new picker writes. (3) Orphans get worse, not better: `isPermissionPathSegment` exists so a name predating the rule stays deletable; once permissions are a fixed list from code, any Keto name not in that list becomes invisible — either give the Users/Groups screens an "unknown permissions held" affordance or decide explicitly to leave them to `curl`.)
 - [ ] Permissions should be a list in code. Since no permissions exists in the database out of the box, but there are a fixed number of permissions in the plugins that the end consumer and user of plain pages can use, these permissions must surface to the UI somehow. The effects is that the permissions page should be deleted completely, and the users and groups pages should gain the functionality to add permissions to their things instead, provided the user have the right permissiosn to do so, of course. Run the product reviewer agent on this todo also.
 - [ ] The seeded admin@plainpages.local are assigned twice to the permission "admin", should only be one, right? (the "admin" permission name can be switched after previous todos have been done)
 - [ ] In Playwright tests, try different resolutions and sizes, from BIG desktop down to tiny phone.