JSON parser DoS prevention

As reported by Claude review, our current JSON parser does not prevent large exponents from exhausting our memory.
The solution proposed by Claude, however, is inflexible: cap the exponent.
For most regular uses that would be OK. For schema validation, though, that might be too restrictive.
Instead, I suggest we just keep the exponent as a separate field for JSON numbers.
The trade off:

• We get arbitrarily large numbers with efficient-ish representation
• We allow users to define schemas with arbitrary numbers

• We need to implement basic operations and might need some float-like behavior in places

L’issue non indica file, test o punti di ingresso. Inizia individuando il parser JSON e la sua rappresentazione dei numeri, quindi determina l’ambito della conservazione degli esponenti e le operazioni di base necessarie; il lavoro sarà considerato completato quando gli esponenti grandi non causeranno più l’esaurimento della memoria e la validazione dello schema continuerà ad accettare numeri arbitrari.