docs(solana): fix types and account instantiation pattern

[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/*

[lucas-tortora]

out of curiosity, why abandon* about?

[ihsraham]

So it's more like Lorem Ipsum. Abandon is at index zero of BIP39 english wordlist. And the last word has to be index 3(about) to keep checksum valid (checksum of all other being at index 0)
So it's like the simplest 12 word mnemonic