fix: elevate CSS priority to override GTK4 user theme (v0.7.2)

Colloid-Catppuccin theme loaded via ~/.config/gtk-4.0/gtk.css at
PRIORITY_USER (800) was overriding moonset's PRIORITY_APPLICATION (600),
causing action buttons to lose their circular border-radius.

- Use STYLE_PROVIDER_PRIORITY_USER for app CSS provider
- Replace border-radius: 50% with 9999px (GTK4 CSS percentage quirk)

CHANGELOG.md

@@ -3,6 +3,13 @@
 All notable changes to this project will be documented in this file.
 Format based on [Keep a Changelog](https://keepachangelog.com/).
 
+## [0.7.2] - 2026-03-29
+
+### Fixed
+
+- Fix CSS priority so app styles override GTK4 user theme (Colloid-Catppuccin) — use `STYLE_PROVIDER_PRIORITY_USER` instead of `STYLE_PROVIDER_PRIORITY_APPLICATION`
+- Replace `border-radius: 50%` with `9999px` — GTK4 CSS does not reliably support percentage-based border-radius
+
 ## [0.7.1] - 2026-03-28
 
 ### Fixed