plan: roles as data, teams as scopes, and the owner as an identity

Design for tomorrow, written down so the work starts from a spec. Phase 0 is
already built; everything after it is plan.

The load-bearing decision is the smallest one. Ownership is answered today by
users.role === 'Super Admin', which was fine while roles were a hardcoded union
and nothing could write a new one — and becomes a privilege-escalation path the
moment roles are editable data, because then adding a role and becoming the owner
are the same feature. So phase 1 is just that: the owner is OWNER_USER_ID, every
existing call site keeps meaning owner, and nothing downstream starts until it
lands.

Teams union rather than restrict, which is the only coherent resolution and has a
consequence worth stating: a team can only ever grant. Deny rules are named under
what must not be built, along with a role that confers ownership and team-scoped
execution capabilities.

And the thing a reader would otherwise discover at the end of phase 4: there is
still no way to create a second account, so this is a permission model for
accounts that cannot yet exist. Sequenced last because it is orthogonal, flagged
because it may be worth doing first.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CLAUDE.md

@@ -477,6 +477,9 @@ explaining why it was safe.
   owner-only while the plugin itself stays grantable. What the proxy should pass (`isOwner` and a level,
   never the role name), why declaring owner-only paths in the manifest beats trusting every plugin to
   remember, and the credential-resolution work that has to land first
+- `docs/roles-and-teams.md` — **plan, phase 0 built**: roles as a table, teams as scopes, and the one
+  change that has to land first — the owner becomes an identity rather than whoever holds a role name,
+  because otherwise "add a role" and "become the owner" are the same feature
 - `docs/localization.md` — **plan, not built**, with a working 5% skeleton already in the tree: taking the
   web UI to more than one language. What exists and what it cannot do yet, why the server should return
   error CODES rather than prose (and why a code must not leak more than the prose it replaced), the key