Major UI refresh: sidebar redesign, theme expansion, and chat performance optimizations (#706)

## Summary
Complete sidebar redesign and comprehensive UI polish pass with performance optimizations, theme system refinements, and desktop integration improvements.

## Key Changes

**Sidebar & Navigation Redesign**
- Redesigned sessions sidebar layout with unified button primitives
- Added activity sections with project grouping and improved session organization
- Refined sidebar corners, spacing, and visual hierarchy
- Removed NavRail component in favor of streamlined sidebar
- Stabilized sessions bar toggle position in fullscreen mode

**Performance Optimizations**
- Reduced chat streaming CPU usage and storage churn
- Optimized task tool polling and live timers with debouncing
- Prevented chat state races and reduced background request load
- Debounced draft writes and coalesced session reloads
- Optimized message store updates and turn tracking

**Theme & Visual System**
- Added theme-aware window corners (desktop) and border radius tokens
- Introduced glassmorphism effects on desktop sidebar
- Added backdrop blur to UI elements

**Chat Experience**
- Added session-based permission auto-accept toggle in chat input
- Polished permission shield UX with improved icon sizing and spacing
- Fixed chat scroll-to-bottom behavior and timeline tracking
- Enhanced tool output display with better path label detection
- Removed duplicate draft context details in chat header
- Added text selection menu to chat messages

**Git Improvements**
- Refreshed git history visual design with cleaner dividers
- Added remote removal action in sync selector
- Stabilized git polling to prevent excessive requests
- Improved tool output rendering for git operations

**Settings & Panels**
- Fixed mobile scrolling on settings pages
- Made outside-click settings close instantly
- Reduced settings load churn and CPU spikes
- Improved services dropdown layout and spacing
- Softened panel resize handles

**Desktop Integration**
- Synced macOS window theme with app theme
- Restored window dragging in sidebar header zones
- Fixed system window corners on macOS
- Improved header session metadata and action controls

**Button & Component Standardization**
- Unified button primitives across all components
- Standardized destructive action patterns
- Removed unused button variants (button-large, button-small)
- Aligned context tab close hit areas

---------

Co-authored-by: Iuliia Ivashko <yulia.ivashko@gmail.com>

packages/ui/src/components/session/sidebar/hooks/useGroupOrdering.ts

@@ -4,13 +4,11 @@ import type { SessionGroup } from '../types';
 export const useGroupOrdering = (groupOrderByProject: Map<string, string[]>) => {
   const getOrderedGroups = React.useCallback(
     (projectId: string, groups: SessionGroup[]) => {
-      const archivedGroup = groups.find((group) => group.isArchivedBucket === true) ?? null;
-      const reorderableGroups = archivedGroup ? groups.filter((group) => group !== archivedGroup) : groups;
       const preferredOrder = groupOrderByProject.get(projectId);
       if (!preferredOrder || preferredOrder.length === 0) {
-        return archivedGroup ? [...reorderableGroups, archivedGroup] : reorderableGroups;
+        return groups;
       }
-      const groupById = new Map(reorderableGroups.map((group) => [group.id, group]));
+      const groupById = new Map(groups.map((group) => [group.id, group]));
       const ordered: SessionGroup[] = [];
       preferredOrder.forEach((id) => {
         const group = groupById.get(id);
@@ -19,12 +17,12 @@ export const useGroupOrdering = (groupOrderByProject: Map<string, string[]>) =>
           groupById.delete(id);
         }
       });
-      reorderableGroups.forEach((group) => {
+      groups.forEach((group) => {
         if (groupById.has(group.id)) {
           ordered.push(group);
         }
       });
-      return archivedGroup ? [...ordered, archivedGroup] : ordered;
+      return ordered;
     },
     [groupOrderByProject],
   );