## Summary
- show relevant unread threads and active agents when hovering a channel
- keep channel-level unread emphasis separate from thread activity dots
- make activity rows navigate to the thread and remove demo-only data
## Test plan
- `just ci` (all stages passed except the final duplicate native check,
which ran out of disk after its earlier clippy pass)
- `cd desktop && pnpm exec playwright test
tests/e2e/channel-activity-popover.spec.ts --project=smoke`
---------
Signed-off-by: kenny lopez <klopez4212@gmail.com>