[C2] Improvements to admin stats

[ywarnier]

In main/admin/statistics/index.php, there are a series of things that do not work correctly or have to be slightly improved:

• in general, the blue bars in any table showing several lines with percentages, are not proportional (they are all filled up to 100%)
• ?report=courses shows a flattened pie chart
• ?report=tools should show the most used tools first ("order by count desc" or something like that)
• ?report=tool_usage should show the most frequent resources first
• ?report=coursebylanguage should show a pie chart
• ?report=pictures shoulkd show the number of users that have uploaded a picture. Apparently, due to the structure change, this is not correct anymore (it just says nobody has uploaded a picture)
• ?report=logins_by_date the selector moves to the bottom of the table of results when you confirm the filter. It should stay on top of the table.
• ?report=no_login_users Should show "Number of users" and the total count of users above the table, otherwise it's difficult to know what those numbers represent.
• ?report=zombies the default date in the calendar seems to be set one year in the past (today it shown 9/2/2025 by default). + some spaces have to be fixed above the table, inside the paginator line and in the total width of the table (long e-mail addresses send the table overflowing to the right of the page)
• ?report=users_active seems to show everything at 0 (except the total, which always shows 100%). Some additional space as margin-bottom of the tables would be good, too.
• ?report=users_online has escaped HTML between the parenthesis (Users online (3′) should be Users online (3')). You can also use the colors for alert, warning, success, information for the 4 different times (same colors for the 2 lines). The least time (3') should show as more "urgent", so more red than 5, 30 and 120 minutes.
• ?report=new_user_registrations on a portal with many users, loading the chart makes my browser crash. It seems like the chart is trying to resize infinitely (higher and higher each time)
• ?report=subscription_by_day seems to have the same chart issue as the previous report
• ?report=activities when clicking a username, an ugly popup (oversized and repeated name, bad sizing in general) opens with a form to send a message to the user. This should send me to the user details page, not open a popup to write to them
• ?report=user_session the Date range box is too small, you can only see the end date. Also, the quick selector lets you choose "next week" but not "last week", which doesn't have a lot of sense for stats (for sessions, maybe you want to see the ones in the future, but there are some other reports where it doesn't make sense) (and you should definitely have "last week" in there)
• ?report=quarterly_report The "Show: All" text should be a link or a button to show all blocks, not just a text
• ?report=session_by_date The form elements should be horizontal (there is space for that). The * Required field legend should have more space below, before the report title. Currently too close together.

[christianbeeznest]

It is checked and improved with this commit cbbcff5

Thanks for confirmation.

[ywarnier]

• The chart in report=courses is still a bit compressed for me

• New: In report=tools, accesses to the glossary tool do not seem to be reported (this is probably due to them not being recorded in the first place?)
• ?report=session_by_date The form elements should be horizontal (there is space for that). The * Required field legend should have more space below, before the report title. Currently too close together.