feat(quickshell): join adjacent panels into a continuous rail

At spacing 0 a row of panels read as separate tiles, each closing its own
silhouette. BarPanel can now drop either cut corner — rightChamfer (top-right)
and leftChamfer (bottom-left), the only two the shape cuts — so an edge that a
neighbour butts against runs square into it. The bar turns off the host's right
and the vitals' left; the tray keeps both, since the spacer between them is not
a panel and that edge is free.

A side with its chamfer off also draws a connector: the shared edge restroked
in accent at outlineWidth + 2, so the join reads as a deliberate seam rather
than two outlines that happen to touch. The outline's own width becomes a
property so the connector can be defined against it instead of as a second
literal.

The lower-right accent strip takes accentLineWidth, the same slug-derived width
the upper-left one already used, instead of its own Math.min(49, width / 3).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HEtXvseVb5gwAtKNhFx2PU

dotfiles/quickshell/hyprchrome/widgets/HyprChromeBar.qml

@@ -100,12 +100,15 @@ Scope {
       x: window.margin
       y: window.margin
       width: window.width - window.margin * 2
-      spacing: 8
+      spacing: 0
 
       HostPanel {
         id: hostPanel
 
         expanded: root.expanded
+        // Vitals butts against its right edge; the left end of the row is free.
+        rightChamfer: false
+
         toggleOnClick: false
         Layout.preferredWidth: 350
         Layout.fillHeight: true
@@ -115,6 +118,10 @@ Scope {
         id: vitalsPanel
 
         expanded: root.expanded
+        // Host on the left, the spacer on the right — and a spacer is not a
+        // panel, so that edge keeps its cut.
+        leftChamfer: false
+
         toggleOnClick: false
         Layout.preferredWidth: 500
         Layout.fillHeight: true