Stop lists and sliders from losing input under the user

WifiList and the notification toasts built their model from a plain
computed array, so any background property tick (a scan result, an
unrelated notification arriving) reassigned the whole array and the
Repeater destroyed and recreated every delegate -- including one with
an open, focused password field or an in-progress reply. Switched
both to a ScriptModel, which diffs by identity instead of resetting.

ValueSlider had its pointer-to-value mapping offset by 16px (the
hit-area margin was applied with the wrong sign), so 0% was
unreachable and every click landed to the right of where it was
placed -- affects every slider in the shell. SliderRow used -1 as a
sentinel for "nothing pending," which collides with legitimate
negative preference values like pointer sensitivity.

Dock intellihide read the globally focused workspace instead of each
monitor's own, so an empty workspace on one screen could hide the
dock on another; ActivityPanel rebuilt every row once a second during
a recording because the elapsed-time read lived in the model
construction instead of each row's own binding.

Claude-Session: https://claude.ai/code/session_01E6TJUAh41HaP25MVHWkhRZ

config/dot/quickshell/widgets/ValueSlider.qml

@@ -103,7 +103,12 @@ Item {
             cursorShape: Qt.PointingHandCursor
 
             function apply(mouseX) {
-                const ratio = Math.max(0, Math.min(1, (mouseX + 8) / track.width));
+                // mouseX is local to this MouseArea, whose anchors.margins: -8
+                // pushes its own origin 8px before the track's left edge. So
+                // MouseArea-local x=8 is track-local x=0 -- subtract the
+                // margin to land back in the track's own coordinate space
+                // before turning it into a fraction.
+                const ratio = Math.max(0, Math.min(1, (mouseX - 8) / track.width));
                 root.moved(ratio);
             }