Support JSON null values (auto-convert to Python None) in toon-python encoding flow

[raksha18-vimo]

Problem Statement

Hi team,
I’m using toon-python to encode tool outputs into TOON. I often receive payloads in JSON format where missing values appear as null, for example:
{
"abc": null,
"xyz": null
}

The only workaround is converting null → None manually, or converting null into "null" (string), which changes the meaning of the data.

Proposed Solution

Request

Could toon-python support one of the following?

Provide a helper function such as:

toon_format.encode_json(json_string: str)

that parses JSON and converts null → None before encoding.

Or provide a utility:

toon_format.loads(json_string)

similar to json.loads(), but TOON-friendly.

Or document clearly that None must be used and provide an official conversion snippet.

Why this matters

This is a very common integration case when data originates from:

1. LLM tool outputs
2. APIs
3. logs / stored JSON payloads
4. Having built-in support would prevent frequent encoding failures and improve developer experience.

Alternatives Considered

No response

SPEC Compliance

No response

Additional Context

No response