feat: Unified wallet architecture with transaction models

[tysonwil]

Swift SDK: Unified Wallet Architecture

Breaking Changes

Removed Dependencies

• web3swift - No longer included
• solana-swift - No longer included
• BigInt dependency moved to internal use only

API Changes

• ❌ ParaEvmSigner class removed - Use signTransaction() with EVMTransaction instead
• ❌ ParaSolanaWeb3Signer class removed - Use signTransaction() with SolanaTransaction instead
• ❌ ParaCosmosSigner class removed - Use signTransaction() with CosmosTransaction instead
• ✅ New unified methods: signMessage(), signTransaction() work with all wallet types

Migration

Before:

import ParaSwift

let evmSigner = ParaEvmSigner()
let signature = try await evmSigner.signTransaction(...)

After:

import ParaSwift

let transaction = EVMTransaction(to: "0x...", value: 1000000000000000000, gasLimit: 21000)
let result = try await para.signTransaction(walletId: walletId, transaction: transaction)
let signature = result.signature

Impact

• External wallet integrations: Unaffected - continue using blockchain SDKs directly for MetaMask, Phantom, etc.
• Para wallet operations: Now use unified interface instead of chain-specific signers
• Package size: Reduced by removing external blockchain dependencies