feature: `registry` service to have other assets

## Overview
Chain registry has registered assets with ibc denom, erc20 tokens as well as factory tokens. These are not currently supported or present in the `/assets` endpoint on the service.

## Proposal
1. Predefined ibc tokens could be initialized and treated like test tokens
2. Scrape IBC tokens from relayers and make them official assets in assetlist for chains

Is it even needed?

Start by locating the registry service and its /assets endpoint, then review how ibc denom, erc20, and factory tokens are currently represented. Clarify whether predefined IBC tokens, relayer scraping, or both are required before implementation. Done means the agreed asset types are present in /assets with coverage for the supported sources.

Written by the indexing model from the issue text.