theme: soften the YoRHa shapes; SUPER+D opens the dashboard

The square markers, block meters and hard-cornered fills read as boxy
next to the porthole. The desktop is now soft throughout: the porthole
is the shape everything is built around and every smaller surface echoes
it.

- Theme gains radiusS / radiusM / radiusL. radiusL is frameRadius - padS,
  so anything inset padS inside one of the frame's curves is concentric
  with it.
- P5Panel and Skew draw rounded rectangles (Geom.roundedRect) whenever
  they neither lean nor are chopped, which is always now; the polygon
  path is kept for shapes brought back on purpose.
- Markers are dots; workspace pips, toggles, transport and media chips,
  notification actions and today's date are pills or discs; the slider
  handle is round. Meters are one continuous rounded line that glides to
  its level instead of a row of segments.
- Album art is rounded with ClippingRectangle in the bar, the media
  popout and the dashboard.
- Free-standing panels (launcher, ask) drop the corner brackets and take
  the frame radius.
- Fix: a hovered notification's wash was a full-bleed square, so in the
  drawer's bottom corner it ran past the drawer's curve. It is inset by
  padS/2 and rounded by radiusL, which keeps it inside the curve.

Hyprland: the discord special workspace and its window rule are gone,
SUPER+S stays the only scratchpad, and SUPER+D now opens the dashboard
(it was on SUPER+I).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

quickshell/popouts/MediaPopout.qml

@@ -1,6 +1,7 @@
 import QtQuick
 import QtQuick.Shapes
 import Quickshell
+import Quickshell.Widgets
 import "root:/config"
 import "root:/components"
 import "root:/services"
@@ -32,14 +33,15 @@ Popout {
             subtitle: Media.identity
         }
 
-        // Cover art in a hairline frame.
-        Rectangle {
+        // Cover art, rounded, in a hairline frame.
+        ClippingRectangle {
             id: artFrame
             anchors.top: header.bottom
             anchors.topMargin: Theme.padM
             anchors.left: parent.left
             width: 108
             height: 108
+            radius: Theme.radiusL
             color: Theme.surface
             border.width: 1
             border.color: Theme.overlay
@@ -216,6 +218,7 @@ Popout {
 
                     Skew {
                         anchors.fill: parent
+                        radius: height / 2
                         color: !chip.enabled
                             ? Theme.treatmentDisabledFill
                             : (chip.activeFocus
@@ -287,6 +290,7 @@ Popout {
 
         Skew {
             anchors.fill: parent
+            radius: width / 2
             color: {
                 if (!tb.enabled) return "transparent";
                 if (tb.activeFocus) return Theme.treatmentFocusFill;