Refactor AI summarizer client initialization to include MongoDB manager and add statistics endpoint

- Updated `InitAISummarizerClient` to accept `mongoManager` for tracking translation success.
- Introduced new `Statistics` endpoint in the dashboard to fetch scraping and translation statistics.
- Enhanced `TranslationWorker` to utilize the new success counter for tracking successful translations.
- Added necessary data structures and query forms for statistics reporting.

This refactor improves the tracking of AI translation success and provides new insights through the dashboard statistics.

internal/dashboard/entity.go

@@ -85,3 +85,24 @@ type RecentItem struct {
 	CreatedAt       int64  `json:"created_at"`
 	PublicationDate int64  `json:"publication_date"`
 }
+
+// StatisticsReportResponse powers the statistics and charts report.
+type StatisticsReportResponse struct {
+	Days        int                      `json:"days"`
+	GeneratedAt int64                    `json:"generated_at"`
+	Daily       StatisticsDailySeries    `json:"daily"`
+	Totals      StatisticsLifetimeTotals `json:"totals"`
+}
+
+// StatisticsDailySeries contains per-day chart series.
+type StatisticsDailySeries struct {
+	ScrapedTED       []TrendPoint `json:"scraped_ted"`
+	ScrapedDocuments []TrendPoint `json:"scraped_documents"`
+	TranslatedNotices []TrendPoint `json:"translated_notices"`
+}
+
+// StatisticsLifetimeTotals contains all-time totals.
+type StatisticsLifetimeTotals struct {
+	ScrapedDocuments  int64 `json:"scraped_documents"`
+	TranslatedTenders int64 `json:"translated_tenders"`
+}