feat: new PAM auth management & settings in greeter/lockscreen

- Introduce external management of greetd PAM
- New functionality to validate and apply custom PAM service paths in lockscreen

Port 1.5

quickshell/Common/SettingsData.qml

@@ -895,6 +895,10 @@ Singleton {
     readonly property bool greeterU2fReady: Processes.greeterU2fReady
     readonly property string greeterU2fReason: Processes.greeterU2fReason
     readonly property string greeterU2fSource: Processes.greeterU2fSource
+    property string lockPamPath: ""
+    property bool lockPamInlineFprint: false
+    property bool lockPamInlineU2f: false
+    property bool greeterPamExternallyManaged: false
     property string lockScreenInactiveColor: "#000000"
     property int lockScreenNotificationMode: 0
     property bool lockScreenVideoEnabled: false

quickshell/Common/settings/SettingsSpec.js

@@ -233,6 +233,7 @@ var SPEC = {
     greeterLockDateFormat: { def: "", onChange: "markGreeterSyncPending" },
     greeterFontFamily: { def: "", onChange: "markGreeterSyncPending" },
     greeterWallpaperFillMode: { def: "", onChange: "markGreeterSyncPending" },
+    greeterPamExternallyManaged: { def: false, onChange: "markGreeterSyncPending" },
     greeterSyncPending: { def: false },
     greeterSyncBaseline: { def: {} },
     mediaSize: { def: 1 },
@@ -455,6 +456,9 @@ var SPEC = {
     maxFprintTries: { def: 15 },
     enableU2f: { def: false, onChange: "scheduleAuthApply" },
     u2fMode: { def: "or" },
+    lockPamPath: { def: "" },
+    lockPamInlineFprint: { def: false },
+    lockPamInlineU2f: { def: false },
     lockScreenInactiveColor: { def: "#000000" },
     lockScreenNotificationMode: { def: 0 },
     lockScreenVideoEnabled: { def: false },