Add gsio-client and gsio-wallet crates with initial implementations

- Introduced `gsio-client` crate for interacting with GSIO nodes, including ledger entry management and node discovery.
- Introduced `gsio-wallet` crate for key management, transaction creation, and wallet functionality.
- Updated workspace configuration to include new crates.

crates/gsio-wallet/README.md

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+# GSIO Wallet
+
+A wallet implementation for the GSIO network.
+
+## Features
+
+- Key management (generate, store, retrieve keys)
+- Transaction creation and signing
+- Balance tracking
+- Transaction history
+
+## Usage
+
+```rust
+use gsio_wallet::{Wallet, TransactionType};
+
+// Create a new wallet
+let mut wallet = Wallet::new();
+
+// Generate a new keypair
+let address = wallet.generate_keypair().unwrap();
+println!("Generated address: {}", address);
+
+// Create a transaction
+let transaction = wallet.create_transaction(
+    &address,
+    "recipient_address",
+    100,
+    10,
+    TransactionType::Transfer,
+    None,
+).unwrap();
+
+// Sign the transaction
+let mut signed_transaction = transaction.clone();
+wallet.sign_transaction(&mut signed_transaction).unwrap();
+
+// Submit the transaction (in an async context)
+async {
+    let tx_id = wallet.submit_transaction(&signed_transaction).await.unwrap();
+    println!("Transaction submitted: {}", tx_id);
+};
+
+// Get account balance
+let balance = wallet.get_balance(&address).unwrap();
+println!("Balance: {}", balance);
+
+// Get transaction history
+let history = wallet.get_transaction_history(&address).unwrap();
+println!("Transaction history: {:?}", history);
+```
+
+## Implementation Details
+
+This is a stubbed implementation of a wallet for the GSIO network. The actual implementation would need to be integrated with the GSIO network to handle real transactions and balances.
+
+The wallet uses Ed25519 for cryptographic operations, which provides strong security for digital signatures.
+
+## Future Improvements
+
+- Implement wallet persistence with encryption
+- Add support for multiple accounts in a single wallet
+- Implement transaction verification
+- Add support for different transaction types
+- Integrate with the GSIO network for real transactions