Build our own "Assets Onchain" Data Pull

[MSilb7]

Today, we rely on L2Beat's API for assets onchain. This is good for coverage of the wide L2/3 market, but it often lags behind internal needs for chains in the Superchain - which can lead to misunderstandings (i.e. Swell is still not listed after being live for weeks. This results in us showing 0 assets onchain, when they publicly celebrate 200m+).

Steps:

1. Collect L1 Bridge contracts Read Chain Metadata from Superchain Registry #1063
2. Get token balance and prices each day Build Tokens Table #934 (TODO: Prices issue - maybe DFL API)
3. Develop methodology for L2 Native / externally bridged tokens (both should appear minted from the null address)