Feature: Visualize failed webhook deliveries for the entire instance

Calculate and visualize the number of failed webhook deliveries per day:
```
cat /var/log/hookshot/resqued.log.1 | grep -e '^\["repository-' | wc -l
```

Start by running or examining the provided resqued.log.1 command and tracing where instance-wide analytics and visualizations are implemented. Done means the system presents the number of failed webhook deliveries for each day across the entire instance; the issue names no files or tests to use.

Written by the indexing model from the issue text.