Drop the unreachable reference-prefix checks

A name starting with ".." also starts with ".", so loadDir's hidden-entry
skip reaches it first and neither isRef branch could ever fire. Removed, and
the comment in named now names the skip that actually holds the invariant it
depends on.

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

data.go

@@ -61,9 +61,6 @@ func loadDir(dir string) (*group, error) {
 		}
 		full := filepath.Join(dir, e.Name())
 		if e.IsDir() {
-			if isRef(e.Name()) {
-				return nil, fmt.Errorf("%s: folder %q starts with %q, which is reserved for {..path} bindings", full, e.Name(), refPrefix)
-			}
 			child, err := loadDir(full)
 			if err != nil {
 				return nil, err
@@ -81,9 +78,6 @@ func loadDir(dir string) (*group, error) {
 			continue
 		}
 		name := strings.TrimSuffix(e.Name(), ".json")
-		if isRef(name) {
-			return nil, fmt.Errorf("%s: category %q starts with %q, which is reserved for {..path} bindings", full, name, refPrefix)
-		}
 		if err := checkName(name); err != nil {
 			return nil, fmt.Errorf("%s: category %w", full, err)
 		}

reference.go

@@ -170,8 +170,8 @@ func contained(n node) []namedNode {
 
 // named skips a bound {..path} key: it is a render edge, not containment, so using
 // it as a path segment would report a node under a path that does not reach it. Only
-// a template's fields hold bindings — loadDir rejects a category or folder carrying
+// a template's fields hold bindings — loadDir skips a dot-prefixed entry, so a
-// the prefix — so this one skip serves a group's children too.
+// group's children never carry the prefix — so this one skip serves both.
 func named(m map[string]node) []namedNode {
 	out := make([]namedNode, 0, len(m))
 	for _, name := range sortedNames(m) {