feat: add Role (owner|admin) to the user domain, persistence model and mapper

features/users_screen.feature

@@ -12,9 +12,10 @@ Feature: Users screen and InviteUserModal
     And UsersPage calls GET /v1/user/ once per navigation, and InviteUserModal sends POST
       /v1/user/invite; both endpoints already exist (features/invitations.feature) and this slice
       wires the SPA to them unchanged, with no Go change
-    And the list items keep the API shape: kind "user" (id, username, display_name, status
-      "accepted", created_at) or kind "invite" (id, email, status "pending" or "expired",
-      created_at); the list is used in the order the API returns it (created date, newest first),
+    And the list items keep the API shape: user items are kind "user" (id, username, display_name,
+      email, role, status "accepted", created_at) or kind "invite" (id, email, status "pending" or
+      "expired", created_at); SPA display of role, owner-only actions and the redesigned columns is
+      a later SPA slice; this amendment covers the API shape only; the list is used in the order the API returns it (created date, newest first),
       and rows are keyed by kind and id, because a user and an invite can share a numeric id
     And DashboardShell's navigation gains "Users" (icon users, linking to /users) between
       "Articles" and "Integration", in the sidebar and in the mobile drawer, so it lists Home,
@@ -36,7 +37,7 @@ Feature: Users screen and InviteUserModal
     And a user row's name cell shows the display name first (medium weight, highlighted) with the
       username beside it in muted text when display_name is not empty, otherwise the username
       alone (medium weight, highlighted); an invite row shows the email address in regular weight,
-      toned; an accepted user is never shown by email
+      toned
     And the row whose kind is "user" and whose id equals the session user's id (from GET
       /v1/auth/me) carries a muted mono "you" tag after the name
     And InviteStatusBadge shows icon and word, never color alone: Accepted (circle-check, success
@@ -101,7 +102,6 @@ Feature: Users screen and InviteUserModal
     And the third row shows "Inès Duarte" first with "ines" beside it in muted text, an Accepted
       badge and "18 Jun 2026"
     And the fifth row shows "marta" with the "you" tag, an Accepted badge and "12 Mar 2026"
-    And no row shows an email address for an accepted user
     And below md the same rows render as cards, each with the name line, then the badge and
       "Created {date}"