Toggles show their state the same way everywhere (#74, #75)

A sweep of all 24 theme palettes, measuring each icon's drawn colour,
found pinned in three colours: accent in the feed list, the text colour
on an item's row, and uncoloured on the toolbar, beside the title and on
the feed page. The read button showed the action (an envelope on a read
item) beside a pin showing the state. Now each toggle shows what is, with
aria-pressed, and a pressed one is the accent colour; Classic needs its
own rule, as its buttons set their colour at higher specificity. The
contrast test checks the accent on the button grounds, where it now draws.

Directory's Subscribe button carried the Subscribed tick; it is a plus.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -30,6 +30,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Pinned and read look the same wherever they are shown, in every theme: the button lights up
+  in the theme's accent colour when it is on. The read button used to show an envelope on a
+  read item, the opposite of how the pin beside it worked.
+- In Directory and Popular, Subscribe is a plus again, not the tick that marks a feed you have.
 - A web page with some non-ASCII characters no longer hides the feed it links, or crashes looking for it.
 - Pulling the item list down to check for new items shows a spinner for a couple of seconds, and
   a second pull meanwhile does nothing, instead of no sign at all that the check started.