* Update class diagrams
* Implement BoundedChannel and multithreaded logging infra
* Integrate logging channel system
* Update string concatenations to use std::format
* Add pretty print log
Rationale:
HTTP is a supporting concern in the pipeline, used only for Wikipedia enrichment calls. libcurl's C API required significant boilerplate to wrap safely. cpp-httplib is a header-only library that covers the same functionality with far less overhead and no manual resource management.
