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/ContextPanel.tsx

@@ -211,7 +211,8 @@ export const ContextPanel: React.FC = () => {
       data-context-panel="true"
       tabIndex={-1}
       className={cn(
-        'flex min-h-0 flex-col overflow-hidden border-l border-border bg-background',
+        'flex min-h-0 flex-col overflow-hidden bg-background',
+        !isExpanded && 'border-l border-border/40',
         isExpanded
           ? 'absolute inset-0 z-20 min-w-0'
           : 'relative h-full flex-shrink-0',