Allow adding 3 custom links to community public pages

[ferranrego]

Enabling communities to add 3 custom links will make the community public pages more useful (see image)

This brings up another issue: the need for short URLs for community public pages, as the current URLs are too long to share easily on platforms like Farcaster (where URL characters are also counted in casts)

• Adding a map field into the smart contract
• Implementing the UI according to the design

[ferranrego]

For now, it will remain in the backlog until we have a clear plan for implementing it in the contract.

@lucasmenendez suggests using Markdown and setting this information in the contract. Needs evaluation.