A UI pass: contrast in every theme, and a sign-in page that fits

Measured every theme's palette against WCAG AA. The unread badge's count
on its --accent2 fill fell as low as 2.6:1 (Flat Remix light), and the
unread dot with it; each theme's --accent2 is taken down until white on
it clears 4.5. Tags were --warn or --bad on --raise, short of AA in most
light themes, so they are outlined on the row's own ground instead.

Nordic dark had --line equal to --panel2, so bordered buttons on a
panel2 ground drew no edge at all. Classic's selected row left the
row's icon buttons grey on the blue. A zero badge on a selected row was
--raise on --raise and vanished.

login.html never had a doctype or viewport meta, so it rendered in
quirks mode and at desktop width on a phone, and its light palette sat
under data-theme="light", which nothing ever set. It follows
prefers-color-scheme now, signed out having no account to ask.

Dropped the unused log and users icons. The Classic theme's label is
now just "Classic".

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

CHANGELOG.md

@@ -13,6 +13,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   instead of toasts: no more "Scanning…" or "1 new" pop-ups, and none at all for feeds you do not read. A
   "Downloaded" toast is only for a file on your screen.
 - "Check every feed" checks every feed you subscribe to, not every feed on the server.
+- The Classic theme is listed in Settings as just "Classic".
+
+### Fixed
+
+- Unread counts, the unread dot and the Gone and Error tags are readable in every theme: several
+  light themes (Flat Remix, Paper, Adwaita, Nordic, Modern) drew them below AA contrast.
+- The sign-in page follows the system's light or dark setting, and fits a phone's screen instead of
+  drawing at desktop width.
+- In Classic, a selected item's play and delete buttons are white on the blue, not grey.
+- In Nordic's dark half, button and toolbar borders show.
+- A zero unread count on the selected feed no longer disappears into the selection.
 
 ## [0.8.0] - 2026-09-18