Use ember-estree minimal API, fix template positions and parent refs

- Use toTree({ templateOnly: true }) instead of processGlimmerTemplate
- Pass inner content (not full <template> tags) fixing 10-col offset
- Removes spurious GlimmerElementNode(tag: "template") wrapper
- Keep local traverse for convertAst scope management
- blockParamNodes now have parent refs (fixes template-no-let-reference)
- Update snapshots for corrected AST structure

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Author: NullVoxPopuli

package.json

@@ -35,7 +35,7 @@
     "@glimmer/syntax": ">= 0.92.0",
     "@typescript-eslint/tsconfig-utils": "^8.38.0",
     "content-tag": "^4.1.0",
-    "ember-estree": "github:NullVoxPopuli-ai-agent/ember-estree#bde42e3",
+    "ember-estree": "github:NullVoxPopuli-ai-agent/ember-estree#bc048bc",
     "eslint-scope": "^9.1.1",
     "html-tags": "^5.1.0",
     "mathml-tag-names": "^4.0.0",