fix: hide sticky save bar on non-config tabs to prevent layout push

The sticky float-right save/cancel bar was rendering (invisible via
opacity-0) on all tabs including runs, causing it to push the runs
layout content. Now only rendered when showConfigActionBar is true.
Also reverts the negative margin workaround from the previous attempt.

Co-Authored-By: Paperclip <noreply@paperclip.ing>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/pages/AgentDetail.tsx

@@ -659,14 +659,9 @@ export function AgentDetail() {
       )}
 
       {/* Floating Save/Cancel (desktop) */}
-      {!isMobile && (
+      {!isMobile && showConfigActionBar && (
         <div
-          className={cn(
-            "sticky top-6 z-10 float-right transition-opacity duration-150",
-            showConfigActionBar
-              ? "opacity-100"
-              : "opacity-0 pointer-events-none"
-          )}
+          className="sticky top-6 z-10 float-right transition-opacity duration-150"
         >
           <div className="flex items-center gap-2 bg-background/90 backdrop-blur-sm border border-border rounded-lg px-3 py-1.5 shadow-lg">
             <Button
@@ -1313,7 +1308,7 @@ function RunsTab({
 
   // Desktop: side-by-side layout
   return (
-    <div className="flex gap-0 -mr-4 md:-mr-6">
+    <div className="flex gap-0">
       {/* Left: run list — border stretches full height, content sticks */}
       <div className={cn(
         "shrink-0 border border-border rounded-lg",