Use a default Web3 provider before wallets are connected

[mhluongo]

Right now, we have a pattern of saying "no data provided" on overview pages.

This pattern is great — we need to have smooth empty states. But it would be nice if we saw it less.

I recommend we use a default Web3 provider before a wallet is connected, using eg Alchemy or Infura, so people can see network-wide data like TVL and reward pools before they commit to connecting their wallets.