feat: move projects to sidebar rail and speed up session switching (#506)

* feat: move projects from header tabs to left sidebar rail

* refactor: remove variant from git generation session context

* feat: implemented drandrop action for navrails

* refactor: improve sidebar drag-and-drop smoothness and remove floating overlay

* fix: prevent mobile nav rail touch from closing drawer and opening menu

* fix: hide header tabs on desktop

* fix: prevent session flicker when switching projects

* style: soften chat panel divider borders

* style: improve icon contrast across core navigation

* fix: stabilize session selection during project switching

* style: unify sidebar surfaces and transparent section layers

* style: remove UI shadows and keep only scroll shadow

* perf: speed up project switching with cached session loading

* perf: speed up Git changes view and background refresh

* perf: make session switching lighter and less aggressive

* perf: optimized sessions list loading while project switching

* perf: smooth chat rendering and reduce interaction spikes

* fix: restore reliable load older messages visibility

packages/ui/src/components/layout/RightSidebarTabs.tsx

@@ -13,8 +13,8 @@ export const RightSidebarTabs: React.FC = () => {
   const setRightSidebarTab = useUIStore((state) => state.setRightSidebarTab);
 
   return (
-    <div className="flex h-full min-h-0 flex-col overflow-hidden bg-sidebar">
-      <div className="border-b border-border/40 bg-background px-3 py-1.5">
+    <div className="flex h-full min-h-0 flex-col overflow-hidden bg-transparent">
+      <div className="border-b border-border/40 bg-transparent px-3 py-1.5">
         <AnimatedTabs<RightTab>
           value={rightSidebarTab}
           onValueChange={setRightSidebarTab}