Review whether User and City registry contracts need to implement extension-trait

[radicleart]

Review whether these two contracts need to implement the extension trait. They're controlled by the dao but do not themselves need to implement extension-trait. This may change as the functionality unfolds.

[whoabuddy]

We should probably leave things as-is now as to eliminate introducing any confusion.

• proposals = one-time actions
• extensions = standing functionality

Also since both contracts use is-dao-or-extension and .base-dao is-extension to determine if its active, it might be more confusing to say this isn't an extension.