feat(run): lay out the Workspace lane strip as a horizontal row above the detail panel

The lane strip was a fixed-width vertical column beside the detail panel.
Flipped it to a horizontally scrolling row on top so the detail/console
area gets the full page width below it.

client/src/pages/Workspace.tsx

@@ -521,15 +521,11 @@ export function Workspace() {
         </button>
       </div>
 
-      {/* Lane list + detail live side by side so neither can cover the other:
-          the list is a scrolling column (holds any number of lanes), the
-          detail/console area to its right never has to compete with it for
-          vertical space. */}
-      <div className="flex min-h-0 flex-1 gap-4">
-        <div
-          data-testid="lane-strip"
-          className="flex w-60 shrink-0 flex-col gap-2 overflow-y-auto pr-1"
-        >
+      {/* Lane strip + detail stack vertically: the strip is a horizontally
+          scrolling row (holds any number of lanes), the detail/console area
+          below it gets the full width and never competes for it. */}
+      <div className="flex min-h-0 flex-1 flex-col gap-4">
+        <div data-testid="lane-strip" className="flex shrink-0 flex-row gap-2 overflow-x-auto pb-1">
           {lanes.map((l) => (
             <LaneStripCard
               key={l.id}

client/src/pages/__tests__/__snapshots__/screens.snapshot.test.tsx.snap

@@ -5762,10 +5762,10 @@ exports[`screen snapshots > Run 1`] = `
       </button>
     </div>
     <div
-      class="flex min-h-0 flex-1 gap-4"
+      class="flex min-h-0 flex-1 flex-col gap-4"
     >
       <div
-        class="flex w-60 shrink-0 flex-col gap-2 overflow-y-auto pr-1"
+        class="flex shrink-0 flex-row gap-2 overflow-x-auto pb-1"
         data-testid="lane-strip"
       >
         <p