The factory declared supportedNetworks: ['mainnet'], so availableWallets
hid Web3Auth on TestNet and every other network. The adapter never reads
the Algorand network: it derives the account from the key Web3Auth
returns, and the address is the same on every network.

Drop the capabilities so Web3Auth is available everywhere, as
WalletConnect is. The README now says web3AuthNetwork picks the Web3Auth
environment, not the Algorand network.

The block hash is the hash of the header, so GetBlockHash now loads
the header with BlockHdr instead of the full block, avoiding loading
and decoding the payset.