theme: sweep everything that isnt using a spacing token from singleton,

add Theme.XXS

quickshell/Modals/FileBrowser/FileBrowserContent.qml

@@ -804,7 +804,7 @@ FocusScope {
                             anchors.topMargin: Theme.spacingS
                             anchors.bottomMargin: Theme.spacingS
                             visible: viewMode === "list"
-                            spacing: 2
+                            spacing: Theme.spacingXXS
                             model: folderModel
                             currentIndex: selectedIndex
                             onCurrentIndexChanged: {

quickshell/Modals/FileBrowser/FileBrowserSidebar.qml

@@ -16,7 +16,7 @@ StyledRect {
     Column {
         anchors.fill: parent
         anchors.margins: Theme.spacingS
-        spacing: 4
+        spacing: Theme.spacingXS
 
         StyledText {
             text: I18n.tr("Quick Access")

quickshell/Modals/FileBrowser/KeyboardHints.qml

@@ -20,7 +20,7 @@ Rectangle {
         anchors.left: parent.left
         anchors.right: parent.right
         anchors.margins: Theme.spacingS
-        spacing: 2
+        spacing: Theme.spacingXXS
 
         StyledText {
             text: I18n.tr("Tab/Shift+Tab: Nav • ←→↑↓: Grid Nav • Enter/Space: Select")