docs(solana): fix types and account instantiation pattern

Created by: ihsraham

Summary

Fixes documentation inaccuracies found during verification against actual SDK TypeScript types.

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Files Changed

1. sdk/wallet-modules/wallet-solana/configuration.md

Issue: Direct WalletAccountSolana constructor example fails at runtime.

Fix: Replace with WalletManagerSolana.getAccount() pattern.

-import { WalletAccountSolana } from '@tetherto/wdk-wallet-solana'
-const account = new WalletAccountSolana(seedPhrase, "0'/0/0", accountConfig)
+import WalletManagerSolana from '@tetherto/wdk-wallet-solana'
+const wallet = new WalletManagerSolana(seedPhrase, accountConfig)
+const account = await wallet.getAccount(0)

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2. sdk/wallet-modules/wallet-solana/api-reference.md

Issue: Return types documented as number but SDK returns bigint.

Fix: Update all method signatures to use correct types.

Method	Before	After
getFeeRates()	{normal: number, fast: number}	{normal: bigint, fast: bigint}
getBalance()	Promise<number>	Promise<bigint>
getTokenBalance()	Promise<number>	Promise<bigint>
sendTransaction()	{hash: string, fee: number}	{hash: string, fee: bigint}
transfer()	{hash: string, fee: number}	{hash: string, fee: bigint}
quoteSendTransaction()	{fee: number}	{fee: bigint}
quoteTransfer()	{fee: number}	{fee: bigint}

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3. sdk/wallet-modules/wallet-solana/usage.md

Issue 1: Code examples used result.signature but SDK returns result.hash.

-console.log('Transaction signature:', result.signature)
+console.log('Transaction hash:', result.hash)

Issue 2: Quick Start used invalid placeholder seed phrase, fails when snippet copied and pasted.

-const seedPhrase = 'your twelve word seed phrase here'
+const seedPhrase = 'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about'

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Verification

Test	Result
API type verification	✅ Passed
Blind copy-paste tests (4 snippets)	✅ Passed
TypeScript compilation	✅ Passed

Related Task

[WDK] Solana: Audit sdk/wallet-modules/wallet-solana/*