feat: complete remaining Go backend modules

backend/internal/administration/model.go

@@ -141,6 +141,30 @@ type UpdateAccountInput struct {
 	Password       *string
 	ClearLoginLock bool
 }
+
+// AccountUpdate is the storage intent for an account PATCH. Implementations
+// must only mutate fields whose pointers/flags are present. In particular,
+// security state that is not part of this intent must remain database-owned so
+// a concurrent password change or login attempt cannot be overwritten by a
+// stale account snapshot.
+type AccountUpdate struct {
+	Actor                   Actor
+	DisplayName             *string
+	Role                    *Role
+	OrganizationID          *string
+	Status                  *Status
+	PasswordHash            *PasswordHash
+	ClearLoginLock          bool
+	IncrementSessionVersion bool
+	UpdatedAt               time.Time
+}
+
+// AtomicAccountUpdater is an optional deep storage seam for implementations
+// that can apply AccountUpdate atomically. Store remains backward compatible
+// for process-local/test adapters; durable stores should implement this seam.
+type AtomicAccountUpdater interface {
+	ApplyAccountUpdate(context.Context, string, AccountUpdate) (Account, error)
+}
 type UpdateOrganizationInput struct {
 	Name   *string
 	Status *Status