fix: llama backend lifetime, Wikipedia enrichment depth, and misc cleanup

pipeline/includes/llama_backend_state.h

@@ -0,0 +1,32 @@
+#ifndef BIERGARTEN_PIPELINE_LLAMA_BACKEND_STATE_H_
+#define BIERGARTEN_PIPELINE_LLAMA_BACKEND_STATE_H_
+
+/**
+ * @file llama_backend_state.h
+ * @brief RAII guard for llama.cpp backend process lifetime.
+ */
+
+#include <llama.h>
+
+/**
+ * @brief RAII wrapper for llama_backend_init and llama_backend_free.
+ *
+ * Create one instance in application startup before using llama.cpp and keep
+ * it alive for application lifetime.
+ */
+class LlamaBackendState {
+  public:
+   /// @brief Initializes global llama backend state.
+   LlamaBackendState() { llama_backend_init(); }
+
+   /// @brief Cleans up global llama backend state.
+   ~LlamaBackendState() { llama_backend_free(); }
+
+   /// @brief Non-copyable type.
+   LlamaBackendState(const LlamaBackendState&) = delete;
+
+   /// @brief Non-copyable type.
+   LlamaBackendState& operator=(const LlamaBackendState&) = delete;
+};
+
+#endif  // BIERGARTEN_PIPELINE_LLAMA_BACKEND_STATE_H_