Implement BoundedChannel and multithreaded logging infra

tooling/pipeline/includes/services/logging/log_entry.h

@@ -0,0 +1,65 @@
+/**
+ * @file services/logging/log_entry.h
+ * @brief POD log entry structure for asynchronous pipeline logging.
+ *
+ * Intent: Lightweight, move-safe data transfer between logging producer
+ * (ChannelLogger) and consumer (LogConsumer) via BoundedChannel<LogEntry>.
+ */
+
+#ifndef BIERGARTEN_PIPELINE_INCLUDES_SERVICES_LOGGING_LOG_ENTRY_H_
+#define BIERGARTEN_PIPELINE_INCLUDES_SERVICES_LOGGING_LOG_ENTRY_H_
+
+#include <chrono>
+#include <string>
+
+/**
+ * @enum LogLevel
+ * @brief Severity levels for log entries.
+ */
+enum class LogLevel {
+   Debug,  ///< Development/debugging information.
+   Info,   ///< General informational messages.
+   Warn,   ///< Warning conditions.
+   Error,  ///< Error conditions.
+};
+
+/**
+ * @enum PipelinePhase
+ * @brief Execution phases for contextual logging.
+ *
+ * Used to tag log entries by their processing stage, enabling phase-specific
+ * analysis and filtering of the execution timeline.
+ */
+enum class PipelinePhase {
+   Startup,                      ///< Initialization and validation.
+   UserGeneration,               ///< User profile generation.
+   BreweryAndBeerGeneration,     ///< Brewery and beer data generation.
+   CheckinGeneration,            ///< Checkin (visit) record generation.
+   RatingGeneration,             ///< Rating and review generation.
+   FollowGeneration,             ///< Follow relationship generation.
+   Teardown,                     ///< Finalization and cleanup.
+};
+
+/**
+ * @struct LogEntry
+ * @brief Single log event for asynchronous processing.
+ *
+ * All fields are value types, allowing safe move semantics across
+ * BoundedChannel without shared ownership or synchronization overhead.
+ */
+struct LogEntry {
+   /// @brief Timestamp when entry was created.
+   std::chrono::system_clock::time_point timestamp =
+       std::chrono::system_clock::now();
+
+   /// @brief Severity level of this entry.
+   LogLevel level;
+
+   /// @brief Pipeline phase when entry was logged.
+   PipelinePhase phase;
+
+   /// @brief Log message text.
+   std::string message;
+};
+
+#endif  // BIERGARTEN_PIPELINE_INCLUDES_SERVICES_LOGGING_LOG_ENTRY_H_