feat: implement proper BIP39/44 HD key derivation with comprehensive tests

[ca333]

feat: implement proper BIP39/44 HD key derivation with comprehensive tests

Summary

This PR implements proper BIP39/BIP44 HD key derivation for offline key export functionality and addresses several code quality issues:

Core Changes:

• Fixed BIP39/44 HD seed generation: Replaced incorrect bip39_seed_from_passphrase() usage with proper GlobalHDAccountCtx::new() and BIP44 derivation paths
• API Naming: Renamed StandardKeysResponse → IguanaKeysResponse and GetPrivateKeysResponse::Standard → GetPrivateKeysResponse::Iguana
• Error Handling: Added specific ProtocolParseError for protocol parsing failures, removed unused HardwareWalletNotSupported/MetamaskNotSupported variants
• Code Cleanup: Removed unused _coins_ctx variable, modified extract_prefix_values to return Option<PrefixValues>
• Test Coverage: Added comprehensive unit tests with test vectors for BTC, BTC-Segwit, ETH, and Atom key derivation

Key Files Modified:

• mm2src/coins/rpc_command/offline_keys.rs: Major refactoring of HD key derivation logic and API structure

Review & Testing Checklist for Human

• CRITICAL: Verify BIP39/44 key derivation produces correct addresses/keys using the test mnemonic: "prosper boss develop coconut warrior silly cabin trial person glass toilet mixed push spirit love"
• CRITICAL: Run the new unit tests (cargo test offline_keys) to ensure they actually pass
• CRITICAL: Test end-to-end HD key export for BTC (m/44'/0'/0'/0/0-2) and verify against expected test vectors
• Verify API backward compatibility - existing consumers using StandardKeysResponse will need updates
• Test error handling flows, especially protocol parsing errors, to ensure no regressions

Recommended Test Plan:

1. Run unit tests: cargo test test_btc_hd_key_derivation test_eth_hd_key_derivation
2. Manual test with test mnemonic for BTC: verify addresses 1DWZWURWrdJnuZBqQgv3THfmhbxWgJuFex, 17jQZo8xSjJeQLxexLZSZaBA9ks5tWh3fJ, 13ZwKLGksE72YgMdKjJC9XZPM6TcpejJrJ
3. Test both HD and Iguana modes to ensure no regressions

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    A["mm2src/coins/rpc_command/<br/>offline_keys.rs"]:::major-edit
    B["crypto::GlobalHDAccountCtx"]:::context
    C["crypto::StandardHDPath"]:::context
    D["BIP39/44 Test Vectors"]:::context
    
    A -->|"uses for proper<br/>HD derivation"| B
    A -->|"uses for<br/>derivation paths"| C
    A -->|"validates against"| D
    
    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit  
        L3["Context/No Edit"]:::context
    end

    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• The original HD seed generation was using bip39_seed_from_passphrase() incorrectly - this has been fixed to use proper BIP44 derivation
• Test vectors provided by user @ca333 are hardcoded in tests but need verification against actual implementation
• Atom test vector was incomplete in original specification, so only first 2 addresses are tested
• This is a breaking change for API consumers using the old StandardKeysResponse naming

Link to Devin run: https://app.devin.ai/sessions/50a4a813d5f049a785689f7e94f30144
Requested by: @ca333

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