feat(ui): P3 间距优化（侧栏gap/分割线加粗品牌色hover）

src/components/layout/app-layout.tsx

@@ -341,7 +341,7 @@ export function AppLayout({ onSwitchProject }: AppLayoutProps) {
               <ActivityPanel />
             </div>
             <div
-              className="w-1.5 shrink-0 cursor-col-resize bg-border/40 transition-colors hover:bg-primary/30 active:bg-primary/40"
+              className="w-2 shrink-0 cursor-col-resize bg-border/40 transition-colors hover:bg-primary/40 active:bg-primary/50"
               onMouseDown={startDrag("left")}
             />
           </>

src/components/layout/icon-sidebar.tsx

@@ -249,14 +249,14 @@ export function IconSidebar({ onToggleSidebar, onOpenSidebar, onSwitchProject }:
           />
         </button>
         {/* Top: configurable feature entries */}
-        <div className="flex flex-1 flex-col items-center gap-1">
+        <div className="flex flex-1 flex-col items-center gap-1.5">
           <DndContext
             sensors={sensors}
             collisionDetection={closestCenter}
             onDragEnd={handleDragEnd}
           >
             <SortableContext items={visibleNavIds} strategy={verticalListSortingStrategy}>
-              <div className="flex flex-col items-center gap-1">
+              <div className="flex flex-col items-center gap-1.5">
                 {visibleNavItems.map((item) => (
                   <SortableNavButton
                     key={item.id}
@@ -272,7 +272,7 @@ export function IconSidebar({ onToggleSidebar, onOpenSidebar, onSwitchProject }:
           </DndContext>
         </div>
         {/* Bottom: daemon status + theme toggle + settings + switch project */}
-        <div className="flex flex-col items-center gap-1 pb-1">
+        <div className="flex flex-col items-center gap-1.5 pb-1">
           {/* Theme selector dropdown */}
           <Tooltip>
             <TooltipTrigger