fix(core): improve DeepResolveType type

[BernieCr]

I think it would be a nice addition to declare snapshots as immutable on Typescript level. This makes it easier for users to notice that they are only supposed to modify the store, not the snapshot.

I also took the liberty to rename the type to Snapshot, it's probably better than DeepResolveTypeReadonly.
Awesome library by the way!

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[dai-shi]

Nice suggestion. Just curious, was the previous typing somehow causing a trouble?

[BernieCr]

Wow, that was a fast code review!

Just curious, was the previous typing somehow causing a trouble?

No, not at all. I am a freelance developer and am looking for state management libraries I could potentially recommend in future projects.
This is easier if other developers that are not familiar with this library and its concepts are automatically prevented from making common mistakes.
I personally played around with this library quite a bit now and did some reading, and know I understand the reason for the creating snapshots and why you can't modify them, but it took some time.

[dai-shi]

Suggested change

	: Readonly<T>
	: T

Looks like we don't need this.
Check this out: https://tsplay.dev/NlxQXN
Or, please let us know the case it might break.

[BernieCr]

Oh yeah that's true, I actually hadn't studied the Readonly<> type in detail.
While checking this I noticed that the Map, Setand Date types aren't immutable with the current implementation. Do you think we should cover those cases as well, or would that be overkill?

[dai-shi]

They are indeed not immutable. So, it's correct. Actually, it's not deterministic. With #321, we could technically change the behavior at runtime. So, we can't provide 100% static type anyway.