Implement algorand, near and stellar signer in gemstone

[0xh3rman]

No description provided.

[gemini-code-assist]

Code Review

This pull request implements transaction signing support for Algorand, Near, and Stellar by introducing chain-specific signers, transaction models, and serialization logic. It also adds utilities for address parsing, checksum verification, and Ed25519 public key derivation. Review feedback focuses on optimizing cryptographic operations and fee parsing, addressing limitations in Stellar asset and memo support, and ensuring network-specific configurations like the Stellar passphrase are handled dynamically.