Manager.Set and Manager.All

Set is the deliberate overwrite: it replaces a registered entry in place,
keeping its position in the insertion order, and falls back to Register
when the name is new. Register keeps panicking on duplicates.

All returns every entry in insertion order; orderedWidgets is now just
that call, and reversedWidgets builds on it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core.manager.go

@@ -33,6 +33,18 @@ func (m *Manager[T]) Register(v T) {
 	m.order = append(m.order, name)
 }
 
+// Set replaces a registered entry in place, keeping its position in the
+// registration order, and registers the entry when the name is new. Register
+// panics on a duplicate; Set is the deliberate overwrite.
+func (m *Manager[T]) Set(v T) {
+	name := v.GetName()
+	if _, ok := m.items[name]; !ok {
+		m.Register(v)
+		return
+	}
+	m.items[name] = v
+}
+
 func (m *Manager[T]) Get(name string) (T, bool) {
 	v, ok := m.items[name]
 	return v, ok
@@ -59,6 +71,15 @@ func (m *Manager[T]) Names() []string {
 	return append([]string(nil), m.order...)
 }
 
+// All returns every registered entry in insertion order.
+func (m *Manager[T]) All() []T {
+	out := make([]T, len(m.order))
+	for i, n := range m.order {
+		out[i] = m.items[n]
+	}
+	return out
+}
+
 func (m *Manager[T]) SortedNames() []string {
 	names := append([]string(nil), m.order...)
 	sort.Strings(names)