v0.2.2: Preferences page, About page, full icon set, redesigned permissions list

- Add a Preferences page (reachable from the hamburger menu) with a
  KColorSchemeManager-backed color scheme switcher
- Add an About page reading from KAboutData
- Ship a full hicolor icon set (16-128px + scalable) via ecm_install_icons
  instead of a single flat SVG
- Restyle the permissions list after KDE System Settings' Audio page:
  Kirigami.ListSectionHeader per category, flat separated rows, no card
  borders
- Explicitly declare Kirigami/KirigamiAddons/ColorScheme as CMake
  dependencies instead of relying on the QML import scanner alone
- Add KDEClangFormat/KDEGitCommitHooks, a CMakePresets.json, and a
  REUSE + clang-format lint CI workflow
- Reformat SPDX headers to include copyright, and tidy up a stray
  namespace inconsistency

icons/CMakeLists.txt

@@ -0,0 +1,16 @@
+# SPDX-FileCopyrightText: 2026 ToServeTheKing <[email protected]>
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+ecm_install_icons(ICONS
+    sc-apps-flatkontrol.svg
+    128-apps-flatkontrol.png
+    64-apps-flatkontrol.png
+    48-apps-flatkontrol.png
+    44-apps-flatkontrol.png
+    32-apps-flatkontrol.png
+    22-apps-flatkontrol.png
+    16-apps-flatkontrol.png
+    DESTINATION ${KDE_INSTALL_ICONDIR}
+    THEME hicolor
+)

icons/sc-apps-flatkontrol.svg

@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
+<!-- SPDX-FileCopyrightText: 2026 ToServeTheKing <[email protected]> -->
 <!-- SPDX-License-Identifier: GPL-3.0-or-later -->
 <svg width="128" height="128" viewBox="0 0 128 128" xmlns="http://www.w3.org/2000/svg">
   <defs>