`JSONEncoder` is incorrectly merging subsequent comments

The following template

```elixir
~S||
```

Is being encoded as:

```
[%{"attrs" => %{}, "content" => [" comment 1 comment 2 "], "tag" => "html_comment"}]
```

It should generate two elements instead of merging into a single comment element.

Start by locating the JSONEncoder entry point that processes the provided Elixir template and inspect how adjacent HTML comments are parsed. Reproduce the example with two consecutive comments, then verify that the encoded result contains two separate html_comment elements rather than one merged content value.

Written by the indexing model from the issue text.