Add more risks to the token integration checklist

There are a couple of risks that we can add:

- Risks associated with tokens that have external calls where the function id is controlled
- Decimals is not always 18
- Risks associated with rebalancing tokens

We have to review past audits to see what else is missing

Start by locating the token integration checklist and reviewing past audits, as requested in the issue. Done means the checklist covers externally controlled function IDs, non-18 decimals, rebalancing-token risks, and any additional justified gaps.

Written by the indexing model from the issue text.