lock: own backdrop with wallpaper option, am/pm clock

The session-lock surface was transparent with nothing painting behind it.
TouchLockSurface now owns its backdrop: lock.wallpaperPath when pinned,
else the system wallpaper, else a dark field — plus a scrim for glance
legibility. Glance clock gains lock.twelveHourClock (default on, h:mm ap).
LockConfig grows the wallpaper picker (same FolderListModel grid as the
wallpaper page, no matugen side effects) and the 12-hour switch.

surfaces/quickshell/modules/common/Config.qml

@@ -457,6 +457,11 @@ Singleton {
                     property real extraZoom: 1.1
                 }
                 property bool centerClock: true
+                // 12-hour glance clock (am/pm). Off = 24-hour.
+                property bool twelveHourClock: true
+                // Lock-screen wallpaper. Empty = follow the system wallpaper
+                // (background.wallpaperPath); a path pins the lock's own.
+                property string wallpaperPath: ""
                 property bool showLockedText: true
                 // Souveraine-owned lock cards. Transport controls are
                 // ambient; media metadata remains personal by default.

surfaces/quickshell/modules/ii/lock/TouchLockSurface.qml

@@ -43,6 +43,35 @@ MouseArea {
     property real dragOffset: 0
     readonly property real commitDistance: 120
 
+    // Lock wallpaper. The session-lock surface is transparent and nothing
+    // else paints behind this MouseArea, so the surface owns its own
+    // backdrop: the lock's pinned wallpaper when set, else the system
+    // wallpaper, else a plain dark field. The scrim keeps the glance text
+    // readable over any image.
+    Rectangle {
+        anchors.fill: parent
+        z: -3
+        color: "#0b0d10"
+    }
+    Image {
+        anchors.fill: parent
+        z: -2
+        source: {
+            const p = Config.options.lock.wallpaperPath
+                || Config.options.background.wallpaperPath || "";
+            return p ? "file://" + p : "";
+        }
+        fillMode: Image.PreserveAspectCrop
+        asynchronous: true
+        visible: status === Image.Ready
+    }
+    Rectangle {
+        anchors.fill: parent
+        z: -1
+        color: "#000000"
+        opacity: 0.32
+    }
+
     function forceFieldFocus() {
         root.forceActiveFocus();
     }

surfaces/quickshell/modules/settings/LockConfig.qml

@@ -1,5 +1,7 @@
 import QtQuick
 import QtQuick.Layouts
+import Qt.labs.folderlistmodel
+import Quickshell
 import qs.services
 import qs.modules.common
 import qs.modules.common.widgets
@@ -89,6 +91,15 @@ ContentPage {
             }
         }
 
+        ConfigSwitch {
+            buttonIcon: "schedule"
+            text: Translation.tr("12-hour clock (am/pm)")
+            checked: Config.options.lock.twelveHourClock
+            onCheckedChanged: {
+                Config.options.lock.twelveHourClock = checked;
+            }
+        }
+
         ConfigSwitch {
             buttonIcon: "text_fields"
             text: Translation.tr("Show locked text")
@@ -117,6 +128,74 @@ ContentPage {
         }
     }
 
+    ContentSection {
+        id: lockWallSection
+        icon: "wallpaper"
+        title: Translation.tr("Lock screen wallpaper")
+
+        readonly property string wallpaperDir: Quickshell.env("HOME") + "/Pictures/Wallpapers"
+
+        ConfigSwitch {
+            buttonIcon: "sync"
+            text: Translation.tr("Follow system wallpaper")
+            checked: !Config.options.lock.wallpaperPath
+            onCheckedChanged: {
+                if (checked) Config.options.lock.wallpaperPath = "";
+            }
+            StyledToolTip {
+                text: Translation.tr("The lock screen shows the same wallpaper as the shell. Pick an image below to pin the lock screen's own.")
+            }
+        }
+
+        GridView {
+            id: lockWallGrid
+            Layout.fillWidth: true
+            readonly property int cols: 3
+            cellWidth: Math.floor(width / cols)
+            cellHeight: Math.floor(cellWidth * 2)
+            implicitHeight: Math.ceil(lockWallModel.count / cols) * cellHeight
+            interactive: false
+            clip: true
+
+            model: FolderListModel {
+                id: lockWallModel
+                folder: "file://" + lockWallSection.wallpaperDir
+                nameFilters: ["*.jpg", "*.jpeg", "*.png", "*.webp"]
+                showDirs: false
+            }
+
+            delegate: Item {
+                required property string filePath
+                width: lockWallGrid.cellWidth
+                height: lockWallGrid.cellHeight
+
+                Rectangle {
+                    anchors.fill: parent
+                    anchors.margins: 5
+                    radius: Appearance.rounding.small
+                    color: Appearance.colors.colLayer1
+                    border.width: Config.options.lock.wallpaperPath === filePath ? 3 : 0
+                    border.color: Appearance.colors.colPrimary
+                    clip: true
+
+                    Image {
+                        anchors.fill: parent
+                        anchors.margins: 3
+                        source: "file://" + filePath
+                        fillMode: Image.PreserveAspectCrop
+                        asynchronous: true
+                        sourceSize.width: 240
+                    }
+
+                    MouseArea {
+                        anchors.fill: parent
+                        onClicked: Config.options.lock.wallpaperPath = filePath
+                    }
+                }
+            }
+        }
+    }
+
     ContentSection {
         icon: "visibility"
         title: Translation.tr("Lock screen content")

surfaces/quickshell/modules/souveraine/lock/LockSurfaceHost.qml

@@ -5,6 +5,7 @@ import QtQuick
 import QtQuick.Layouts
 import Quickshell.Services.UPower
 import qs.services
+import qs.modules.common
 import "."
 
 Item {
@@ -34,7 +35,8 @@ Item {
 
         Text {
             Layout.fillWidth: true
-            text: Qt.formatTime(clock.now, "hh:mm")
+            text: Qt.formatTime(clock.now,
+                Config.options.lock.twelveHourClock ? "h:mm ap" : "hh:mm")
             color: "white"
             font.pixelSize: root.compact ? 60 : 76
             font.weight: Font.Light