Move contextual tips labels away from the normal window subtitle

Nobody has claimed this yet.

## Use case

the window subtitle currently covers several use cases:

- displaying an explicit confirmation of what the current tool is (shape/pencil/etc)
- and of its main options (rectangle/dashed/etc.)
- and contextual help for this tool (click on some button to apply whatever)
- and contextual tips for this tool (press some modifier to toggle some option)

this is not very accessible, as screenreaders are confused by the periodic change

as a user i know it changes, but it's still a pain to wait to have the label i'm looking for

## Suggested solution

near the tool options' popover (or the minimap?), there should be a help popover, for AT LEAST the tips

the button already exists for a handful of tools, but it directly opens the manual

### Possible drawbacks

such a popover has to be hidden on mobile

but mobile user couldn't read long subtitles anyway lol so not a real drawback

### Possible alternatives

no

Start by locating the window subtitle that displays tool names, options, help, and tips, then review the existing tool-options popover and the button that opens the manual. Define how tips should move into a separate help popover, including its mobile visibility and screenreader behavior; done means the subtitle no longer periodically changes for these tips and the new help remains available.

Written by the indexing model from the issue text.