refactor: align component check with ember-cli#2724 canonical (lists + scope)

Remove the inline PascalCase-regex isComponentInvocation heuristic in
favor of the lists + scope pattern from ember-cli#2689 / ember-cli#2724. The new
lib/utils/is-native-element.js mirrors ember-cli#2724's util byte-for-byte so
the two PRs can land in either order without conflict.

evaluateChild / evaluateChildren now thread sourceCode through the
recursion so the scope check has access to the enclosing template's
bindings.

Heuristic approaches were explicitly rejected in ember-cli#2689 because lowercase
tags CAN be components when shadowed by scope bindings. Treating custom
elements as opaque (the same as components) is a behavior improvement
— matches ember-cli#2724's convention.

Author: johanrd

lib/rules/template-anchor-has-content.js

@@ -1,20 +1,4 @@
-// Matches a tag string that is a component invocation rather than a plain
-// HTML element: PascalCase (`Foo`), argument-invocation (`@foo`), path on
-// `this.` (`this.foo`), dotted path (`foo.bar`), or named-block-style
-// `foo::bar`. Keep this mirrored with the inline pattern in
-// lib/rules/template-no-invalid-interactive.js until a shared utility lands.
-function isComponentInvocation(tag) {
-  if (!tag) {
-    return false;
-  }
-  return (
-    /^[A-Z]/.test(tag) ||
-    tag.startsWith('@') ||
-    tag.startsWith('this.') ||
-    tag.includes('.') ||
-    tag.includes('::')
-  );
-}
+const { isNativeElement } = require('../utils/is-native-element');
 
 function isDynamicValue(value) {
   return value?.type === 'GlimmerMustacheStatement' || value?.type === 'GlimmerConcatStatement';
@@ -73,7 +57,7 @@ function hasAccessibleNameAttribute(node) {
 //   { accessible: true }    — statically contributes a non-empty name.
 //   { accessible: false }   — contributes nothing (empty text, aria-hidden
 //                             subtree, <img> without non-empty alt, …).
-function evaluateChild(child) {
+function evaluateChild(child, sourceCode) {
   if (child.type === 'GlimmerTextNode') {
     const text = child.chars.replaceAll('&nbsp;', ' ').trim();
     return { dynamic: false, accessible: text.length > 0 };
@@ -97,8 +81,9 @@ function evaluateChild(child) {
       return { dynamic: false, accessible: false };
     }
 
-    // Component invocations are opaque — we can't see inside them.
-    if (isComponentInvocation(child.tag)) {
+    // Non-native children (components, custom elements, scope-shadowed tags)
+    // are opaque — we can't see inside them.
+    if (!isNativeElement(child, sourceCode)) {
       return { dynamic: true, accessible: false };
     }
 
@@ -124,16 +109,16 @@ function evaluateChild(child) {
       return { dynamic: false, accessible: true };
     }
 
-    return evaluateChildren(child.children || []);
+    return evaluateChildren(child.children || [], sourceCode);
   }
 
   return { dynamic: false, accessible: false };
 }
 
-function evaluateChildren(children) {
+function evaluateChildren(children, sourceCode) {
   let dynamic = false;
   for (const child of children) {
-    const result = evaluateChild(child);
+    const result = evaluateChild(child, sourceCode);
     if (result.accessible) {
       return { dynamic: false, accessible: true };
     }
@@ -162,6 +147,7 @@ module.exports = {
   },
 
   create(context) {
+    const sourceCode = context.sourceCode || context.getSourceCode();
     return {
       GlimmerElementNode(node) {
         if (node.tag !== 'a') {
@@ -179,7 +165,7 @@ module.exports = {
           return;
         }
 
-        const result = evaluateChildren(node.children || []);
+        const result = evaluateChildren(node.children || [], sourceCode);
         if (result.accessible || result.dynamic) {
           return;
         }