Desktop: channel browser renders every channel with '#' — private channels are indistinguishable from open ones (sidebar shows a lock)

{channel.name}

`channel.visibility` appears exactly once in that file, in the filter and not in the rendering (`:183`):

```tsx
(channel.archivedAt ? channel.isMember : channel.visibility === "open" || channel.isMember)
```

The sidebar gets it right — `desktop/src/features/sidebar/ui/SidebarSection.tsx:242-244`:

```tsx
if (channel.visibility === "private") {
return ;
}
```

Note the browser also uses `#` for forum channels, while the sidebar uses `FileText` (`SidebarSection.tsx:246-248`) — same root cause: the row does not consult the channel's type or visibility at all.

## Reproduce

1. Create or join a private channel and a public channel in the same community.
2. Open the channel browser (Add channel).
3. Both rows show `#`. Nothing marks the private one as private.
4. The sidebar shows a lock on the private channel.

## Expected

The browser row uses the same icon logic as the sidebar: lock for `visibility === "private"`, `FileText` for forum channels, `#` otherwise. Extracting the existing sidebar helper would keep the two views from drifting again.

## Note on the filter

The filter itself is correct — a non-open channel only appears when `isMember` is true, so this is a labeling defect, not a disclosure of private channels the viewer is not in.