feat: KYC-compliant coin example

[chariskms]

Adds a simple PAS example showing a KYC registry, a custom coin, and treasury logic enforcing KYC checks for minting and transfers with clawback support.

[manolisliolios]

nit: Let's avoid direct function imports and make it so that we can see the module, e.g.

kyc_registry::approve_clawback

I think it becomes clearer to the reader

[manolisliolios]

Looks like a great base example.

I'd consider adding some documentation to accompany this demo, what's your thinking there? (we should also ask Jessie)

[chariskms]

Looks like a great base example.

I'd consider adding some documentation to accompany this demo, what's your thinking there? (we should also ask Jessie)

I would like to align it with the Quickstart page and add references there for each code snippet that point to the corresponding example.
I am also preparing an unlock example, as we discussed.