feat(cohort): add searchable event dropdowns - #89

⚠️ Doistbot reviewed an earlier commit (b18a535).

Original result: 5 findings (4 P2, 1 P3)

Inline review comments from the original run are still on this PR; they were against the prior commit and may not reflect the current diff. Comment @doistbot /review to re-run against the latest commit.