Safe Transaction Builder

Loads owners, threshold and nonce, then asks the Safe itself for the transaction hash rather than reconstructing the EIP-712 struct locally — Safe versions differ, and a hash that disagrees collects signatures that can never be used. Tracks progress toward the threshold and packs the collected signatures in ascending owner order, which execTransaction requires. Flags DelegateCall prominently, since it runs foreign code inside the Safe with access to everything. The hash comes from the Safe itself rather than being rebuilt locally, so it is correct across Safe versions. Signatures are collected in this browser and are not stored anywhere; closing the tab loses any not yet exported. A DelegateCall runs foreign code inside the Safe and is flagged prominently.