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/chat/ChatMessage.tsx

@@ -920,7 +920,7 @@ const ChatMessage: React.FC<ChatMessageProps> = ({
                         displayParts.length === 0 ? null : (
                         <FadeInOnReveal>
                             <div className="flex justify-end">
-                                <div style={{ backgroundColor: 'var(--chat-user-message-bg)' }} className="max-w-[85%] rounded-2xl rounded-br-sm px-5 py-3 shadow-sm border border-primary/5">
+                                <div style={{ backgroundColor: 'var(--chat-user-message-bg)' }} className="max-w-[85%] rounded-2xl rounded-br-sm px-5 py-3 shadow-none border border-primary/5">
                                     <MessageBody
                                         messageId={message.info.id}
                                         parts={displayParts}