Make flake self-contained - consolidate installer-replication

BREAKING CHANGE: Remove external dots-hyprland dependency

- Imported all essential configs from dots-hyprland/installer-replication
- Added complete configs/ directory with:
  - hypr/ - Hyprland configuration
  - quickshell/ - Quickshell widgets and config
  - applications/ - Application configurations
  - scripts/ - Utility scripts
  - matugen/ - Material You theming
- Updated flake.nix to use local ./configs instead of external repo
- Simplified update-flake script (removed external repo management)
- Updated README to reflect self-contained architecture
- All builds pass with local configurations

Benefits:
- No external repository dependencies
- Faster builds (no network dependencies)
- Version controlled configs in single repo
- Easier maintenance and development
- Complete installer replication in one place

configs/quickshell/modules/common/widgets/SelectionGroupButton.qml

@@ -0,0 +1,24 @@
+import QtQuick.Controls
+import QtQuick.Layouts
+import Quickshell
+import Quickshell.Io
+import Quickshell.Hyprland
+import qs.services
+import qs.modules.common
+import qs.modules.common.widgets
+
+GroupButton {
+    id: root
+    horizontalPadding: 12
+    verticalPadding: 8
+    bounce: false
+    property bool leftmost: false
+    property bool rightmost: false
+    leftRadius: (toggled || leftmost) ? (height / 2) : Appearance.rounding.unsharpenmore
+    rightRadius: (toggled || rightmost) ? (height / 2) : Appearance.rounding.unsharpenmore
+    colBackground: Appearance.colors.colSecondaryContainer
+    contentItem: StyledText {
+        color: parent.toggled ? Appearance.colors.colOnPrimary : Appearance.colors.colOnSecondaryContainer
+        text: root.buttonText
+    }
+}