Export Bitcoin Gateway functions

[fadeev]

Existing Bitcoin wallets DO provide signer interfaces, but they're inconsistent and incomplete. Here's the current state:

Unisat :

window.unisat = {
  getPublicKey: () => Promise<string>,
  signMessage: (message: string) => Promise<string>,
  signPsbt: (psbt: string) => Promise<string>, // :white_check_mark: PSBT support
  signTx: (tx: any) => Promise<string>
}

Xverse:

window.xverse.BitcoinProvider = {
  connect: () => Promise<{ addresses: Array<{ address: string, publicKey: string }> }>,
  signTransaction: (tx: any) => Promise<string>, // :x: No PSBT support
  signMessage: (message: string) => Promise<string>
}

Leather:

window.LeatherProvider = {
  request: (method: string, params?: any) => Promise<any> // Generic RPC
}

Current Pain Points:

• Inconsistent PSBT Support: Only Unisat has native signPsbt() - others require workarounds
• Public Key Access: Some wallets expose public keys, others don't
• Network Detection: No standardized way to detect mainnet/testnet
• Address Derivation: Each wallet handles address formats differently
  What I'm Proposing is a standardized interface that normalizes these differences.
  So, I think this isn't a new standard - it's a compatibility layer that:
• Wraps existing wallet APIs
• Provides consistent PSBT signing across all wallets
• Ensures public key access is always available
• Normalizes network detection

Benefits for ZetaChain:

• Single interface works with Unisat, Xverse, Leather, and future wallets
• No need to handle wallet-specific quirks in your core logic
• Consistent PSBT signing for your TSS gateway integration

[fadeev]

Our implementation must be compatible with Dynamic's Bitcoin connector:

https://www.dynamic.xyz/blog/dynamics-bitcoinkit