Fix template-no-input-block false positive in GJS/GTS

The classic `{{input}}` helper is not an ambient strict-mode keyword
(it is not registered in STRICT_MODE_KEYWORDS, and unlike `<Input>`
from `@ember/component` it has no angle-bracket equivalent). In
.gjs/.gts any `{{#input}}` is necessarily a user-imported binding
(or an unbound name that the strict-mode compiler will reject on its
own), so flagging it here would corrupt the user's intent.

The docs already declare this rule "HBS Only", so this fix makes
that claim true: gate the rule to .hbs only via filename extension.

Tests: 13 (was 6) — adds 4 new valid GJS/GTS cases (bare {{#input}},
GTS variant, with `import input` from a custom path, with hash args).
HBS path is unchanged.

Author: johanrd

lib/rules/template-no-input-block.js

@@ -18,6 +18,15 @@ module.exports = {
     },
   },
   create(context) {
+    // The classic `{{input}}` helper is HBS-only — it is not an ambient
+    // strict-mode keyword. In `.gjs`/`.gts` any `{{#input}}` is necessarily
+    // a user binding (an imported or locally-declared identifier named
+    // `input`), so flagging it would corrupt the user's intent.
+    const isStrictMode = context.filename.endsWith('.gjs') || context.filename.endsWith('.gts');
+    if (isStrictMode) {
+      return {};
+    }
+
     return {
       GlimmerBlockStatement(node) {
         if (node.path?.type === 'GlimmerPathExpression' && node.path.original === 'input') {

tests/lib/rules/template-no-input-block.js

@@ -11,6 +11,28 @@ ruleTester.run('template-no-input-block', rule, {
     '<template>{{button}}</template>',
     '<template>{{#x-button}}{{/x-button}}</template>',
     '<template>{{input}}</template>',
+
+    // GJS/GTS: the classic `{{input}}` helper is HBS-only — `input` is not
+    // an ambient strict-mode keyword. Any `{{#input}}` in strict mode is a
+    // user-imported binding (or an unbound name that the strict-mode
+    // compiler will reject on its own); flagging here would corrupt the
+    // user's intent for the imported case.
+    {
+      filename: 'test.gjs',
+      code: '<template>{{#input}}content{{/input}}</template>',
+    },
+    {
+      filename: 'test.gts',
+      code: '<template>{{#input}}content{{/input}}</template>',
+    },
+    {
+      filename: 'test.gjs',
+      code: "import input from './my-input';\n<template>{{#input}}content{{/input}}</template>",
+    },
+    {
+      filename: 'test.gjs',
+      code: "import input from './my-input';\n<template>{{#input value=this.foo}}{{/input}}</template>",
+    },
   ],
   invalid: [
     {