Refactor BiergartenDataGenerator to use dependency injection container

pipeline/includes/services/wikipedia_service.h

@@ -0,0 +1,32 @@
+#ifndef BIERGARTEN_PIPELINE_WIKIPEDIA_SERVICE_H_
+#define BIERGARTEN_PIPELINE_WIKIPEDIA_SERVICE_H_
+
+/**
+ * @file services/wikipedia_service.h
+ * @brief Wikipedia summary retrieval service with in-memory caching.
+ */
+
+#include <memory>
+#include <string>
+#include <string_view>
+#include <unordered_map>
+
+#include "services/enrichment_service.h"
+#include "web_client/web_client.h"
+
+/// @brief Provides cached Wikipedia summary lookups for city and country pairs.
+class WikipediaService final : public IEnrichmentService {
+  public:
+   /// @brief Creates a new Wikipedia service with the provided web client.
+   explicit WikipediaService(std::shared_ptr<WebClient> client);
+
+   /// @brief Returns the Wikipedia-derived context for a location.
+   [[nodiscard]] std::string GetLocationContext(const Location& loc) override;
+
+  private:
+   std::string FetchExtract(std::string_view query) const;
+   std::shared_ptr<WebClient> client_;
+   std::unordered_map<std::string, std::string> cache_;
+};
+
+#endif  // BIERGARTEN_PIPELINE_WIKIPEDIA_SERVICE_H_