Add multithreaded logging infrastructure for preparation for future designs (#225)

* Update class diagrams

* Implement BoundedChannel and multithreaded logging infra

* Integrate logging channel system

* Update string concatenations to use std::format

* Add pretty print log

tooling/pipeline/src/data_generation/llama/generate_user.cc

@@ -4,9 +4,8 @@
  * retry handling, and output sanitization for downstream parsing.
  */
 
-#include <spdlog/spdlog.h>
 
-#include <stdexcept>
+#include <format>
 #include <string>
 
 #include "data_generation/llama_generator.h"
@@ -21,5 +20,5 @@
 // 4. Return locale-aware username and biography
 UserResult LlamaGenerator::GenerateUser(const std::string& locale) {
   return {.username = "test_user",
-          .bio = "This is a test user profile from " + locale + "."};
+          .bio = std::format("This is a test user profile from {}.", locale)};
 }