Favicon, level file icons, and a feed error mark in the triangle's column

- The logo as favicon, squared up (it is 128x121), at /favicon.png and at
  /favicon.ico outside the auth layer, where a browser asking on its own got a
  401; an apple-touch-icon on white (#32).
- An item not yet downloaded had its download bar on a line of its own under the
  file icon, lifting the icon above its row's; the bar now sits under it without
  taking space (#31).
- A feed error is Font Awesome's exclamation, hung in the margin where a folder's
  triangle is, in the same column; a folder holding a failing feed has its
  triangle turn red.

Closes #31, #32.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -19,8 +19,9 @@ The long form, with what was wrong before and how it was found, is in
 
 ### Changed
 
-- A feed that fails to check gets a red ! in the feed list, and its page says why, in place of a
-  pop-up per failure that everyone saw during a scan of every feed.
+- A feed that fails to check gets a red exclamation mark in the feed list, in the margin where a
+  folder's triangle sits, and its page says why, in place of a pop-up per failure that everyone
+  saw during a scan of every feed. A folder holding a failing feed has its triangle turn red.
 - The theme is chosen in Settings only; the button beside the iPodderX name is gone.
 - Add a feed asks only for the feed; Popular and Directory in the sidebar are where you browse.
 - On a phone, an item's files, with play and delete, sit above its show notes rather than below
@@ -34,6 +35,10 @@ The long form, with what was wrong before and how it was found, is in
 
 - Switching tabs straight after marking everything read no longer shows the previous tab's
   items: of two lists asked for at once, only the later one is shown.
+- ipx has a favicon: the logo, squared up, also at /favicon.ico for browsers that ask there on
+  their own, and on white for an iPhone's home screen.
+- The file icon of an item not yet downloaded sits level with the rest of its row, instead of
+  higher than a downloaded one's.
 - An item you open stays read. A list refresh that crossed with marking it read could put its
   unread dot back until the next refresh.
 - On the Unread tab, the item you were reading leaves the list as soon as you move to the next