Dashboard Improvements

List only the tasks that are trivial to implement.
Non-trivial tasks will be ignored.

- ✔️ Double-clicking on the chart buttons shouldn't lead to the text selection.
- There should be a refresh button for an individual chart, displayed on hover.
- ✔️ The global reload button should always be displayed and should display something like 🗘.
- ✔️ If at least one chart returns an authentication error, show the URL/user/password in the style of a modal dialog, hiding everything else.
- It should be possible to have the user and URL parameters outside of the global base64-encoded state.
- ✔️ Very compact and lightweight LZ77 compression for the base64-encoded state (plenty of options in ~1KB of JS).
- If a query returned a single value or a string, make a beautiful display of this value instead of a chart.
- ✔️ "Add chart" should scroll to the added chart.
- If I edited the chart while other charts were zoomed in, the resulting chart should also be zoomed in.