Support Gnosis Safe as signer for 0x01 → 0x02 withdrawal credential upgrade

**Problem**
When upgrading withdrawal credentials from 0x01 → 0x02 (EIP-7002) via Launchpad’s Validator Actions, the transaction must be signed by the current withdrawal address. For many validators, that address is a Safe (ex-Gnosis Safe).

Currently, the Launchpad only allows connections with MetaMask, Fortmatic or hardware wallets through MetaMask. This excludes Safe users, even though Safe is a fully valid withdrawal address type.

This is a problem, because:
• A large portion of professional stakers and DAOs use a Safe for validator withdrawal addresses.
• Without Launchpad support, Safe users must manually encode calldata and push it through the Safe UI, which is error-prone and undermines Launchpad’s purpose of abstracting away the low-level details.
• Supporting Safe ensures more validators can safely upgrade to 0x02 and benefit from portable withdrawal credentials.

**Possible approaches**
• WalletConnect integration with Safe (Safe already supports WalletConnect v2).
• Native Safe App that opens Launchpad inside the Safe interface.
• Direct support in Launchpad for Safe SDK, similar to how other dApps integrate multisig accounts.

**Suggested outcome**
Allow Safe accounts to connect to Launchpad for validator actions so they can sign the 0x01 → 0x02 upgrade transaction directly, just as EOAs or hardware wallets can. This would significantly reduce operational risk for stakers who rely on Safe.

Start at Launchpad’s Validator Actions entry point and trace the existing MetaMask, Fortmatic, and hardware-wallet connection and signing flow. Compare the listed WalletConnect, Native Safe App, and Safe SDK approaches. Done means Safe accounts can connect to Launchpad and sign the 0x01 → 0x02 upgrade transaction directly.

Written by the indexing model from the issue text.