Bridge commands duplicate signer construction and miss new signer types

[palango]

Summary

Three bridge commands bypass BaseCommand's wallet construction and reimplement it, so any signer type added to BaseCommand silently does not work for them.

Detail

packages/cli/src/commands/bridge/deposit.ts, withdraw-prove.ts and withdraw-finalize.ts each declare async init() {} to skip BaseCommand.init(), then build their own wallet client in a private getL1WalletClient(). That method re-implements the --useLedger / --privateKey branching already present in BaseCommand.getWalletClient() (packages/cli/src/base.ts:229-308):

// packages/cli/src/commands/bridge/deposit.ts:149-162
} else if (res.flags.privateKey) {
  const account = privateKeyToAccount(ensureLeading0x(res.flags.privateKey))
  if (res.flags.from && !isAddressEqual(res.flags.from, account.address)) { ... }
  return createWalletClient({ account, chain: config.l1Chain, transport: http(l1RpcUrl) })
}

The duplication is understandable — these commands sign against L1, not the L2 chain --node points at, so they need a different chain and transport. But the signer selection logic is identical and has been copied rather than shared.

Why it matters

The branching is an exhaustive if/else if over signer types. Any signer added to BaseCommand — a keystore option, a new HSM, anything — works everywhere except these three commands, with no compile-time error and no runtime warning. The user just silently gets a different (or no) signer.

Suggested fix

Extract signer selection from chain/transport binding in BaseCommand, so a command can ask for "the configured signer, bound to this chain and transport". The bridge commands then pass their L1 chain and transport into the shared helper instead of re-deriving the account. That collapses three copies into one and makes new signer types work everywhere by construction.

Context

Found while scoping a --keystore option (like cast --keystore). That work is deliberately scoped to BaseCommand and will not cover the bridge commands, so --keystore will not work with bridge:deposit, bridge:withdraw-prove or bridge:withdraw-finalize until this is addressed.