Add API Implementation to HTTP Client

[taobig]

• Added AccountsByL1Address method to HTTPClient for querying account information using an L1 address.
• Added GetTx method to HTTPClient for retrieving transaction details by hash or sequence index.

[chaoticpunk]

https://github.com/elliottech/lighter-go/pull/22/files#diff-58375ba15a8f77629e996225e7d166bbb86d8af147fe1fdd9e0c8a8b2df77774R138-R154

I think the fixed code has some logical errors

if-else if` stops after first true condition.

if txHash != "" {
    params["by"] = "hash"
    params["value"] = txHash
} else if sequenceIndex != "" {  // ← This gets skipped if txHash != ""
    params["by"] = "sequence_index"  // ← Never runs when both have values
    params["value"] = sequenceIndex
}

When both parameters have values:

• Only txHash is used
• sequenceIndex is completely ignored

Fixed Code:

func (c *HTTPClient) GetTx(txHash, sequenceIndex string) (*TxInfo, error) {
    // Check parameters first
    if txHash == "" && sequenceIndex == "" {
        return nil, fmt.Errorf("must provide either txHash or sequenceIndex")
    }
    if txHash != "" && sequenceIndex != "" {
        return nil, fmt.Errorf("cannot provide both txHash and sequenceIndex")
    }
    
    result := &TxInfo{}
    params := map[string]any{}
    if txHash != "" {
        params["by"] = "hash"
        params["value"] = txHash
    } else {
        params["by"] = "sequence_index"
        params["value"] = sequenceIndex
    }
    
    err := c.getAndParseL2HTTPResponse("api/v1/tx", params, result)
    if err != nil {
        return nil, err
    }
    return result, nil
}

[taobig]

@chaoticpunk I've updated the comments and emphasized how to use parameters in the code annotations. I don’t think it’s necessary to enforce a constraint at the code level that only one parameter can be passed.