New workload: http_logs (1998 FIFA World Cup web logs)

Port the OSB `http_logs` workload. ~31 GB of web server logs; widely used benchmark across the search engine community. Time-series heavy, large-scale log workload complementary to `eventdata`.

> ⚠️ **Prerequisite:** Source data carries an HP copyright with a non-commercial restriction. **Get legal clearance from ASF Infra/Legal before any work begins.**

## Tasks
- Obtain legal clearance
- Convert OSB workload using `solr-orbit convert-workload`
- Define operations: time-range queries, status faceting, bulk indexing
- Add 1k sample corpus for test-mode
- Check whether any operations belong in `common_operations/` rather than this workload

**Depends on:** #3 (ASF dataset hosting must be resolved before corpus files can be finalised)

## References
- OSB workload: https://github.com/opensearch-project/opensearch-benchmark-workloads/tree/main/http_logs
- Creating workloads: https://github.com/apache/solr-orbit/blob/main/CREATE_WORKLOAD_GUIDE.md

Start with the referenced OSB http_logs workload and CREATE_WORKLOAD_GUIDE.md, then inspect the solr-orbit convert-workload command. Confirm legal clearance and resolve the #3 dataset-hosting dependency before finalising corpus files; done means the converted workload includes the agreed operations and a 1k test-mode sample.

Written by the indexing model from the issue text.