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/handler.go

@@ -161,6 +161,30 @@ func (h *Handler) Recent(c echo.Context) error {
 	return response.Success(c, out, "Recent tenders retrieved successfully")
 }
 
+// Statistics returns scraping and translation statistics for charts.
+// @Summary Dashboard statistics report
+// @Description Daily and lifetime statistics for TED scraping, document scraping, and AI translation
+// @Tags Admin-Dashboard
+// @Produce json
+// @Param days query int false "Days back for daily series (default 14, max 90)"
+// @Success 200 {object} response.APIResponse{data=StatisticsReportResponse}
+// @Failure 500 {object} response.APIResponse
+// @Router /admin/v1/dashboard/statistics [get]
+// @Security BearerAuth
+func (h *Handler) Statistics(c echo.Context) error {
+	query := StatisticsQuery{
+		Days: parseIntQuery(c, "days", 0),
+	}
+
+	out, err := h.service.Statistics(c.Request().Context(), query)
+	if err != nil {
+		return response.InternalServerError(c, "Failed to load dashboard statistics")
+	}
+
+	setPrivateCache(c, 60)
+	return response.Success(c, out, "Dashboard statistics retrieved successfully")
+}
+
 func parseIntQuery(c echo.Context, name string, fallback int) int {
 	raw := c.QueryParam(name)
 	if raw == "" {