json-enc extension converts boolean values to strings when sending JSON to serve

## Issue Description

The `htmx-ext-json-enc` extension (version 2.0.0) is converting JavaScript boolean values to strings when serializing data to JSON, which causes type errors when the server expects actual boolean values.

## Expected Behavior

When using the json-enc extension with boolean values:

```html

Submit

```

The JSON sent to the server should contain actual boolean values:

```json
{
"isForced": true
}
```

## Actual Behavior

The extension is sending string representations of boolean values:

```json
{
"isForced": "true"
}
```

This causes type errors on the server side when using strongly-typed languages like Go:

Start by reproducing the provided htmx-ext-json-enc example with hx-vars containing a boolean, then trace the extension's JSON serialization path. Done means the request payload contains a JSON boolean rather than the string "true", including when sent to a strongly typed server.

Written by the indexing model from the issue text.