:sig
DTree json_decode(String s)

:params
s : string containing JSON data
return value : a DTree object containing the deserialized JSON data

:desc
Deserializes 's' into a DTree structure.

The returned structure is usually consumed through `DTree` accessors such as:
- `tree["key"].to_string()`
- `tree["count"].to_u64()`
- `tree["enabled"].to_bool()`

Current runtime note:
- JSON objects and arrays become map-shaped `DTree` values
- JSON booleans become native `bool` `DTree` values
- JSON strings become native `String` `DTree` values
- JSON numbers currently deserialize as string-valued `DTree` nodes, so typed conversions like `to_f64()` and `to_u64()` are the normal way to read numeric content

:see
DTree
json_encode
to_bool
to_f64
to_u64

:related
**PHP:** `json_decode()`
**JavaScript / Node.js:** `JSON.parse()`