[Request] Notes view (card)

## Describe the feature
It would be nice to have a place to store notes about targets. This would just be freeform text that users enter.

Need to determine how to associate notes with targets. Probably by `matchExpression`. All notes can be retrieved, or by default only retrieve ones that have an expression matching a specific target. This way users can define a `connectUrl`-based expression to associate a note with a specific (long-lived) "pet" target instance, or define some other criteria to associate the note with a class of targets deployed as "cattle".

No files, tests, or entry points are named. First resolve how notes associate with targets—by matchExpression, connectUrl, or another criterion—and define retrieval behavior. Done means a notes view supports freeform notes and the association and retrieval rules are specified and implemented.

Written by the indexing model from the issue text.