One file icon, green when downloaded; mark unread is an envelope

- The separate check (and warning) beside a file's type icon is gone:
  the type icon itself is green once the file is downloaded and red when
  the download failed, with the details in its tooltip. One icon per row
  keeps the column lined up. On Classic's blue selection they are a
  lighter green and red rather than white.
- Mark unread under an item's title was a solid circle, which read as a
  record button. It is Font Awesome's closed envelope now.
- Drops the unused circle-check, circle-exclamation and circle icons.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016HdTEWQNrzyFULijigkmMn

CHANGELOG.md

@@ -37,10 +37,10 @@ The long form, with what was wrong before and how it was found, is in
   Download latest dialogs (save, download, cancel). The icons are Font Awesome Free, embedded as
   SVG: only the ones used, no font to download, and nothing fetched from anyone else. They
   replace font characters such as ⟳ ⤓ ↗, which came out thin and tiny and differed from font to
-  font. Keep is a flag everywhere, as it was in the original.
-- A file's state and type are icons: a check when it is downloaded, a warning when it failed
-  (the error is in the tooltip), and nothing while it waits; audio, video, image, PDF, torrent
-  and other files each have their own. The DOWNLOADED and PENDING labels are gone.
+  font. Keep is a flag everywhere, as it was in the original, and mark unread is an envelope.
+- A file's type is an icon (audio, video, image, PDF, torrent, other), green once it is
+  downloaded and red when the download failed, with the details in its tooltip. One icon per
+  row keeps the column lined up. The DOWNLOADED and PENDING labels are gone.
 
 ### Security