fix(datasets): fix oversized buttons UI + populate linked_dashboard_count in list endpoint

StatsBar — переделаны огромные карточки-кнопки в компактные пилюли
(rounded-full px-3 py-1 text-sm вместо p-3 grid grid-cols-4).

DatasetList — экшн-кнопки из bg-primary в outline-стиль, карточки
плотнее (p-2.5, py-0.5), ESLint-фиксы (#each key).

Backend — linked_dashboard_count теперь заполняется в списке датасетов
через /dataset/{id}/related_objects (конкурентно, Semaphore=3, timeout=10s).
Ранее поле было только в get_dataset_detail и StatsBar показывал 0.

backend/src/core/superset_client/_datasets.py

@@ -51,6 +51,36 @@ class SupersetDatasetsMixin:
                 )
             return result
     # #endregion SupersetClientGetDatasetsSummary
+    # #region SupersetClientGetDatasetLinkedDashboardCount [TYPE Function] [C:2]
+    # @PURPOSE: Fetch the number of dashboards linked to a dataset via related_objects endpoint.
+    # @RELATION: CALLS -> [APIClient]
+    # @RATIONALE Added to fix linked_count=0 in StatsBar. Reuses the same /dataset/{id}/related_objects call
+    # that get_dataset_detail() was already making, but as a lightweight count-only call.
+    # @REJECTED Enriching get_datasets_summary() with more columns rejected — Superset list endpoint
+    # doesn't include linked_dashboard_count (it's a computed field from related_objects).
+    def get_dataset_linked_dashboard_count(self, dataset_id: int) -> int:
+        with belief_scope("get_dataset_linked_dashboard_count", f"id={dataset_id}"):
+            try:
+                related_objects = self.network.request(
+                    method="GET", endpoint=f"/dataset/{dataset_id}/related_objects"
+                )
+                if isinstance(related_objects, dict):
+                    if "dashboards" in related_objects:
+                        dashboards_data = related_objects["dashboards"]
+                    elif "result" in related_objects and isinstance(
+                        related_objects["result"], dict
+                    ):
+                        dashboards_data = related_objects["result"].get("dashboards", [])
+                    else:
+                        dashboards_data = []
+                    return len(dashboards_data)
+                return 0
+            except Exception as e:
+                app_logger.warning(
+                    f"[get_dataset_linked_dashboard_count][Warning] Failed to fetch related dashboards for dataset {dataset_id}: {e}"
+                )
+                return 0
+    # #endregion SupersetClientGetDatasetLinkedDashboardCount
     # #region SupersetClientGetDatasetDetail [TYPE Function] [C:3]
     # @PURPOSE: Fetches detailed dataset information including columns and linked dashboards.
     # @RELATION: CALLS -> [SupersetClientGetDataset]