fix(solana): normalize RPC transaction handling

[zerone-jang]

Summary

• send maxRetries as a JSON number so strict Solana RPC servers accept sendTransaction
• derive transaction and bundle expiry checks from getEpochInfo().blockHeight
• add unit coverage for option serialization and block-height polling

Context

@solana/kit types maxRetries as bigint, which serializes to \"0\". Solana RPC servers expect a JSON number and reject the request with -32602 Invalid params.

We also observed proxied RPC endpoints intermittently returning the slot for single-request getBlockHeight calls. Since slots exceed lastValidBlockHeight, this prematurely terminates the confirmation loop. getEpochInfo().blockHeight remained consistent across the same endpoints.

These changes were validated with two confirmed Solana swaps through the existing RPC path.

Test plan

• pnpm --filter @lifi/sdk-provider-solana test:unit (58 passed)
• pnpm --filter @lifi/sdk-provider-solana check:types
• pnpm --filter @lifi/sdk-provider-solana build
• pnpm check
• workspace type and circular dependency checks via pre-commit hook

[changeset-bot]

🦋 Changeset detected

Latest commit: 58e0b43

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@lifi/sdk-provider-solana	Patch

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