While I'm away

Erik, Aron: These are priorities for while I'm away:

## Erik

- [x] Dark-deploy approaches for maintainers. Priority is that Jonathan can start uploading videos. Communicate to maintainers that they can start adding the introductions file. That's enough for now.
- [x] Add a column for `feedback_added_at` to `exercise_representations`. Set it when feedback is first added. Update existing representations that have feedback to their `updated_at` column.
- [ ] Add notifications for when feedback is first added to a representation. Notifications should be sent for any solutions where the most recent iteration matches the representation. Pivot on the feedback type:
- Essential: All iterations
- Recommended: If iteration was created in the last 2 weeks
- Optional: No notifications
- [x] Add a new status for `celebratory` next to essential/recommened/optional.
- [ ] Add rest of approaches stuff
- [ ] Work on Track Dashboard stuff.

## Aron
- [x] Tweak the representation UI bit (with the link to read first and spacing) with Tai.
- [x] Build out the track dashboard page. Use stub data for now, and then Erik can give you data.
- Do it in HAML
- Work in `app/views/tracks/build.html.haml`.
- Add a link to config/routes.rb to L134 for `get :build, on: :member` to make it accessible
- Add a stylesheet to `app/css/pages/track-build.css` with any repeating stuff in. You can use just normal details/summary HTML for the collapsable stuff rather than bothering with React.
- [ ] Spend some time with Erik doing system tests, and add them for the components you've added so far
- [x] Fix pagination in any places where the page doesn't reset to `1` when you change filters.

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## Notes

- [ ] Vimeo
- [ ] Agree reputation for authors/contributors
- [x] Check table name for approaches authors
- [x] The unlock button should be available if either:
- solutions.downloaded_at.present?
- submissions.size > 0
- [x] The tab should be available if either:
- iterations.size > 0
- Unlocked button was clicked
- [ ] Hide learning exercises when concepts aren't launched.