feat: Asset Hub migration and elastic scaling preparation - Array responses for useRcBlock, remove rcAt in favor of useRcBlock

[TarikGul]

Summary

This PR updates all endpoints that support useRcBlock parameters to return array responses in preparation for Asset Hub migration and Polkadot/Kusama elastic scaling. This enables support for multiple Asset Hub blocks per
relay chain block while maintaining backward compatibility. This PR also removes any use of rcAt in favor of useRcBlock.

useRcBlock

• useRcBlock works in conjunction with at, unless its a /blocks endpoint which will use the block number in the path, or header if no block is supplied.

Response Structure Changes

WithuseRcBlock parameters:

[
  {
    "at": {...},
    "data": "...",
    "rcBlockNumber": "5678901",
    "ahTimestamp": "1234567890"
  }
]

When no Asset Hub blocks found:

[]

Without these parameters (unchanged):

{
  "at": {...},
  "data": "..."
}

Affected Endpoints

Account Endpoints with useRcBlock

• /accounts/{accountId}/asset-balances
• /accounts/{accountId}/asset-approvals
• /accounts/{accountId}/pool-asset-balances
• /accounts/{accountId}/pool-asset-approvals
• /accounts/{accountId}/balance-info
• /accounts/{accountId}/staking-info
• /accounts/{accountId}/staking-payouts
• /accounts/{accountId}/vesting-info
• /accounts/{accountId}/proxy-info

Block Endpoints with useRcBlock

• /blocks/head
• /blocks/{blockId}
• /blocks/{blockId}/header
• /blocks/head/header
• /blocks/{blockId}/extrinsics/{extrinsicIndex}
• /blocks/{blockId}/extrinsics-raw
• /blocks (range queries)

Pallets Endpoints with useRcBlock

• /pallets/asset-conversion/next-available-id
• /pallets/asset-conversion/liquidity-pools
• /pallets/assets/{assetId}/asset-info
• /pallets/{palletId}/consts
• /pallets/{palletId}/consts/{constantItemId}
• /pallets/{palletId}/dispatchables
• /pallets/{palletId}/dispatchables/{dispatchableItemId}
• /pallets/{palletId}/events
• /pallets/{palletId}/events/{eventItemId}
• /pallets/{palletId}/errors
• /pallets/{palletId}/errors/{errorItemId}
• /pallets/foreign-assets
• /pallets/nomination-pools/info
• /pallets/nomination-pools/{poolId}
• /pallets/ongoing-referenda
• /pallets/pool-assets/{assetId}/asset-info
• /pallets/staking/progress
• /pallets/staking/validators
• /pallets/{palletId}/storage
• /pallets/{palletId}/storage/{storageItemId}

Usage

Using useRcBlock parameter:

const response = await fetch('/accounts/123/balance-info?at=5000000&useRcBlock=true');
const data = await response.json();

if (data.length === 0) {
  console.log('No Asset Hub blocks found');
} else {
  data.forEach(item => {
    console.log(item.free);
    console.log(item.rcBlockNumber);
  });
}

Standard usage (unchanged):

const response = await fetch('/accounts/123/balance-info');
const data = await response.json();
console.log(data.free); // Single object response

Backward Compatibility

Regular queries without useRcBlock continue to return single objects unchanged. Only queries using these parameters now return arrays.