[Dashboard] Fix: If only one time period has analytics events (#5886)

## Notes for the reviewer
Adds an edge case if a user only has events for a single time period. Previously, this would show 0 in the analytics summary since it normally takes the most recent *complete* time period. Now, it falls back to show the incomplete period if there is no complete period with data.

## How to test
Run the dashboard and view the project client ID listed in the linear ticket

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## PR-Codex overview
This PR focuses on improving the handling of time series data in the `aggregateFn` function by ensuring that if there is only one data point, it uses that point instead of the previous one. This change is applied in two files.

### Detailed summary
- Updated `aggregateFn` in `apps/dashboard/src/app/team/[team_slug]/[project_slug]/page.tsx`:
  - Added logic to check if there is only one valid data point.
  - If only one point exists, it uses the last data point; otherwise, it uses the previous one.

- Updated `aggregateFn` in `apps/dashboard/src/app/team/[team_slug]/(team)/~/analytics/page.tsx`:
  - Similar logic added as in the previous file to handle time series data appropriately.

> ✨ Ask PR-Codex anything about this PR by commenting with `/codex {your question}`

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Author: gregfromstl

apps/dashboard/src/app/team/[team_slug]/(team)/~/analytics/page.tsx

@@ -257,7 +257,10 @@ function UsersChartCard({
       }
       data={timeSeriesData}
       aggregateFn={(_data, key) =>
-        timeSeriesData[timeSeriesData.length - 2]?.[key]
+        // If there is only one data point, use that one, otherwise use the previous
+        timeSeriesData.filter((d) => (d[key] as number) > 0).length >= 2
+          ? timeSeriesData[timeSeriesData.length - 2]?.[key]
+          : timeSeriesData[timeSeriesData.length - 1]?.[key]
       }
       // Get the trend from the last two COMPLETE periods
       trendFn={(data, key) =>

apps/dashboard/src/app/team/[team_slug]/[project_slug]/page.tsx

@@ -279,7 +279,10 @@ function UsersChartCard({
       queryKey="usersChart"
       data={timeSeriesData}
       aggregateFn={(_data, key) =>
-        timeSeriesData[timeSeriesData.length - 2]?.[key]
+        // If there is only one data point, use that one, otherwise use the previous
+        timeSeriesData.filter((d) => (d[key] as number) > 0).length >= 2
+          ? timeSeriesData[timeSeriesData.length - 2]?.[key]
+          : timeSeriesData[timeSeriesData.length - 1]?.[key]
       }
       // Get the trend from the last two COMPLETE periods
       trendFn={(data, key) =>