FIX: Exporting overall sentiment fails (#1388)

## 🔍 Overview

When exporting an Overall Sentiment report in the admin panel, the export fails with:

```ruby
Job exception: no implicit conversion of Symbol into Integer
```

This was happening because we are passing a single _Hash_ to `report.data` however, exports expect `report.data` to be an _Array of Hashes_. This update fixes this issue by wrapping the data in an array.

lib/sentiment/sentiment_dashboard_report.rb

@@ -42,15 +42,17 @@ module DiscourseAi
 
           return report if grouped_sentiments.empty?
 
-          report.data = {
-            req: "overall_sentiment",
-            color: report.colors[:lime],
-            label: I18n.t("discourse_ai.sentiment.reports.overall_sentiment"),
-            data:
-              grouped_sentiments.map do |gs|
-                { x: gs.posted_at, y: gs.public_send("sentiment_count") }
-              end,
-          }
+          report.data = [
+            {
+              req: "overall_sentiment",
+              color: report.colors[:lime],
+              label: I18n.t("discourse_ai.sentiment.reports.overall_sentiment"),
+              data:
+                grouped_sentiments.map do |gs|
+                  { x: gs.posted_at, y: gs.public_send("sentiment_count") }
+                end,
+            },
+          ]
         end
       end
     end

spec/lib/modules/sentiment/entry_point_spec.rb

@@ -55,9 +55,23 @@ RSpec.describe DiscourseAi::Sentiment::EntryPoint do
         sentiment_classification(pm, positive_classification)
 
         report = Report.find("overall_sentiment")
-        overall_sentiment = report.data[:data][0][:y].to_i
+        overall_sentiment = report.data[0][:data][0][:y].to_i
         expect(overall_sentiment).to eq(0)
       end
+
+      it "exports the report without any errors" do
+        sentiment_classification(post_1, positive_classification)
+        sentiment_classification(post_2, negative_classification)
+        sentiment_classification(pm, positive_classification)
+
+        exporter = Jobs::ExportCsvFile.new
+        exporter.entity = "report"
+        exporter.extra = HashWithIndifferentAccess.new(name: "overall_sentiment")
+        exported_csv = []
+        exporter.report_export { |entry| exported_csv << entry }
+        expect(exported_csv[0]).to eq(["Day", "Overall sentiment (Positive - Negative)"])
+        expect(exported_csv[1]).to eq([post_1.created_at.to_date.to_s, "0"])
+      end
     end
 
     describe "post_emotion report" do