fix(auth): make the owner role real — provisioning, staff doors, panel guards

Found live while verifying the admin email-edit fix: the Owner account could
not load /api/v1/users at all. Root cause: migration 0011 adds the 'owner'
role and gates every user-administration route on it, but NOTHING ever wrote
it. break-glass (UpsertOwner), the setup MC-bind (CompleteOwnerSetup), and the
re-provision path all forced 'admin', so in a fresh install the entire
owner tier — list/create/edit/disable/delete users, quotas, sessions — was
unreachable. The role was a dead letter in the other direction too: staff
predicates that predate the role did not know it.

- UpsertOwner and CompleteOwnerSetup now write role='owner'; the username-
  conflict arm re-asserts it, which is also the documented pre-0011 promotion
  path ("re-provision via break-glass"). InsertOperator stays plain 'admin'.
- Staff doors learn the role: op-login start/finish admit the Owner; the
  player email door refuses it like any staff account; the in-game approver
  check already used staffRole.
- Reclaim protection: IsProtectedAdminLink (and the break-glass bootstrap
  switch AdminExists) count admin OR owner — the Owner must never be displaced
  by a Mojang-priority reclaim.
- Panel guards make migration 0011's claim true now that owner rows exist: an
  owner can never be demoted, deleted, or disabled through the API (only the
  local break-glass console resets the identity); username/email edits still
  work.

Tests: pgint pins both provisioning paths, the protected-link predicate and
the reset/promote semantics; hermetic suites cover the owner-admitting staff
door, the owner-refusing player door, the three panel guards, and break-glass
attribution.

internal/api/handlers_auth_email_test.go

@@ -510,12 +510,20 @@ func TestLoginEmailPurposeSeparation(t *testing.T) {
 // a wrong code for a staff address answers the same invalid_code as for anyone, and
 // the 403 costs the valid code (verify-then-refuse), so it cannot be farmed as an
 // is-this-address-staff oracle.
+// Staff means admin AND owner (migration 0011): both must be refused at the
+// player door, after the code proves mailbox control.
 func TestLoginEmailVerifyRefusesStaff(t *testing.T) {
+	for _, role := range []string{"admin", "owner"} {
+		t.Run(role, func(t *testing.T) { verifyStaffRefusedAtPlayerDoor(t, role) })
+	}
+}
+
+func verifyStaffRefusedAtPlayerDoor(t *testing.T, role string) {
 	repo := newFakeRepo()
 	repo.settings[LocalAuthEnabledKey] = []byte("true")
 	repo.staff["owner"] = &StaffUser{
 		ID: "a1", Username: "owner", Email: "[email protected]",
-		Role: "admin", EmailVerified: true,
+		Role: role, EmailVerified: true,
 	}
 	mailer := &captureMailer{}
 	api := newTestAPI(repo, newFakeCluster())