feat(ops): add usage_logs partition status to ops dashboard

Add partition management integration to the smart ops system:
- Backend: Add GetUsageLogsPartitionStatus endpoint in OpsHandler
- Backend: Add partition query methods in OpsRepository
- Backend: Add UsageLogsPartitionStatus type in OpsService
- Frontend: Add OpsPartitionStatusCard component
- Frontend: Add partition status display in OpsDashboard
- i18n: Add Chinese and English translations

The partition status card shows:
- Whether usage_logs is partitioned
- Current row count vs threshold (100K)
- Partition count (if partitioned)
- Warning message when partitioning is recommended

This allows administrators to monitor partition status directly
from the ops dashboard without checking server logs.

backend/internal/handler/admin/ops_handler.go

@@ -923,3 +923,22 @@ func parseOpsDuration(v string) (time.Duration, bool) {
 		return 0, false
 	}
 }
+
+// ==================== Usage Logs Partition Management ====================
+
+// GetUsageLogsPartitionStatus returns partition status of usage_logs table.
+// GET /api/v1/admin/ops/partition-status
+func (h *OpsHandler) GetUsageLogsPartitionStatus(c *gin.Context) {
+	if h.opsService == nil {
+		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
+		return
+	}
+
+	status, err := h.opsService.GetUsageLogsPartitionStatus(c.Request.Context())
+	if err != nil {
+		response.ErrorFrom(c, err)
+		return
+	}
+
+	response.Success(c, status)
+}