Tighten sidebar row spacing on touch devices

Mobile Safari still felt overly spaced after the prior touch-target
fix. Bring projects, agents, top-level nav items, the New Issue
button, and section headers down a notch on coarse pointers, and
shrink the gap between sections. Desktop spacing is unchanged.

- Nav items / New Issue button: py-2 -> py-1.5
- Project / agent rows: py-1.5 -> py-1
- Section headers: py-1.5 -> py-1
- Inter-section gap: gap-4 -> gap-3

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/components/Sidebar.tsx

@@ -71,13 +71,13 @@ export function Sidebar() {
         </Button>
       </div>
 
-      <nav className="flex-1 min-h-0 overflow-y-auto scrollbar-auto-hide flex flex-col gap-4 px-3 py-2">
+      <nav className="flex-1 min-h-0 overflow-y-auto scrollbar-auto-hide flex flex-col gap-4 pointer-coarse:gap-3 px-3 py-2">
         <div className="flex flex-col gap-0.5">
           {/* New Issue button aligned with nav items */}
           <button
             onClick={() => openNewIssue()}
             data-slot="icon-button"
-            className="flex items-center gap-2.5 px-3 py-2 text-[13px] font-medium text-muted-foreground hover:bg-accent/50 hover:text-foreground transition-colors"
+            className="flex items-center gap-2.5 px-3 py-2 pointer-coarse:py-1.5 text-[13px] font-medium text-muted-foreground hover:bg-accent/50 hover:text-foreground transition-colors"
           >
             <SquarePen className="h-4 w-4 shrink-0" />
             <span className="truncate">New Issue</span>

ui/src/components/SidebarAgents.tsx

@@ -118,7 +118,7 @@ function SidebarAgentItem({
           if (isMobile) setSidebarOpen(false);
         }}
         className={cn(
-          "flex min-w-0 flex-1 items-center gap-2.5 px-3 py-1.5 pr-8 text-[13px] font-medium transition-colors",
+          "flex min-w-0 flex-1 items-center gap-2.5 px-3 py-1.5 pointer-coarse:py-1 pr-8 text-[13px] font-medium transition-colors",
           isActive
             ? "bg-accent text-foreground"
             : "text-foreground/80 hover:bg-accent/50 hover:text-foreground"

ui/src/components/SidebarNavItem.tsx

@@ -41,7 +41,7 @@ export function SidebarNavItem({
       onClick={() => { if (isMobile) setSidebarOpen(false); }}
       className={({ isActive }) =>
         cn(
-          "flex items-center gap-2.5 px-3 py-2 text-[13px] font-medium transition-colors",
+          "flex items-center gap-2.5 px-3 py-2 pointer-coarse:py-1.5 text-[13px] font-medium transition-colors",
           isActive
             ? "bg-accent text-foreground"
             : "text-foreground/80 hover:bg-accent/50 hover:text-foreground",

ui/src/components/SidebarProjects.tsx

@@ -99,7 +99,7 @@ function ProjectItem({
           if (isMobile) setSidebarOpen(false);
         }}
         className={cn(
-          "flex items-center gap-2.5 px-3 py-1.5 text-[13px] font-medium transition-colors",
+          "flex items-center gap-2.5 px-3 py-1.5 pointer-coarse:py-1 text-[13px] font-medium transition-colors",
           activeProjectRef === routeRef || activeProjectRef === project.id
             ? "bg-accent text-foreground"
             : "text-foreground/80 hover:bg-accent/50 hover:text-foreground",

ui/src/components/SidebarSection.tsx

@@ -151,7 +151,7 @@ function SidebarSectionHeader({
   );
 
   return (
-    <div className="group/sidebar-section px-3 py-1.5">
+    <div className="group/sidebar-section px-3 py-1.5 pointer-coarse:py-1">
       <div className="relative flex min-h-6 min-w-0 items-center gap-1">
         {collapsible ? (
           <CollapsibleTrigger asChild>