Revert pinned items rising to the top of their list

Sorting by the pin column, or the Pinned tab, was enough. order_sql loses its
pinned_first option, pinning no longer reloads the list, and the tests and
changelog line for #35 go. The NULLS FIRST/LAST ordering from the Postgres work
stays.

Closes #36.

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

CHANGELOG.md

@@ -17,11 +17,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - The database is reached through SeaORM, on the way to Postgres (issue #18); it is still the
   same SQLite file, and nothing you see changes. On Postgres, sorting by title or feed follows
-  the language's order (an accented letter beside the plain one) rather than raw bytes. A database from before 0.7 has to be opened by a
-  0.7 release first, which brings its tables up to date.
-- A pinned item sits at the top of its list, above everything else in whatever order you sort
-  by, and moves there the moment you pin it. Sorting by the pin column itself still goes both
-  ways, and Currently Listening keeps its own order.
+  the language's order (an accented letter beside the plain one) rather than raw bytes. A
+  database from before 0.7 has to be opened by a 0.7 release first, which brings its tables up
+  to date.
 
 ## [0.7.0] - 2026-09-18