Persistent and globally searchable feedback log

Feedback generated during a Grady session is logged, and tutors can search their own feedbacks - which is great! But the log should be available across sessions and globally searchable by reviewers.

Use cases

Quality control by Reviewers: Reviewer observes outliers in the tutors statistics, tries to check some of the feedbacks/grading given by outliers.

Links / references

Feature checklist

• SOLVED: This was a usage error (WAS: actually I don't see my yesterday feedbacks, it tells me: No data available, but I definitely gave some (few) feedbacks).

• Feature request: The reviewer should be able to see/search ALL feedbacks given - at least after all submissions have been corrected.

• Nice to have: Link from Tutor statistics to list of feedbacks given by particular tutor.

(Make sure these are completed before closing the issue, with a link to the relevant commit.)