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/DOCUMENTATION.md

@@ -3,24 +3,29 @@
 ## Refactor result
 
 - `SessionSidebar.tsx` now acts mainly as orchestration; core logic moved to focused hooks/components.
-- Sidebar behavior stays intact: global+archived session grouping, folder operations, delete/archive semantics, project/worktree rendering, and search.
-- Recent migration gaps were fixed (persistence + repo-status hooks fully wired).
+- Sidebar is now a single multi-project tree: `recent` top section, then projects, then worktrees/archived groups, then sessions.
+- `NavRail` is no longer part of sidebar/navigation flow.
+- Project headers now own root sessions directly; there is no separate rendered `project root` subgroup.
+- Active/hover row styling is text-first; selected sessions use primary text instead of background fills.
+- Archived groups are collapsed by default and support bulk deletion at group/folder level.
+- Session rows support compact inline dates in minimal mode and simplified metadata in default mode.
 - New extractions in latest pass reduced local effect/callback bulk further:
   - project session list builders
   - folder cleanup sync
   - sticky project header observer
-- Baseline checks pass after refactor: `type-check`, `lint`, `build`.
 
 ## File summaries
 
 ### Components
 
-- `SidebarHeader.tsx`: Top header UI (project selector/rename, search, add/open actions, notes/worktree entry points).
-- `SidebarProjectsList.tsx`: Main scrollable list renderer for project sections/groups, empty states, and project-level interactions.
-- `SessionGroupSection.tsx`: Renders a single group (root sessions + folders), collapse/expand, and group-level controls.
-- `SessionNodeItem.tsx`: Renders one session row/tree node with metadata, menu actions, inline rename, and nested children.
+- `SidebarHeader.tsx`: Top header UI for add-project, session search, and display mode.
+- `SidebarActivitySections.tsx`: Global top section renderer; currently used for the `recent` section only.
+- `SidebarFooter.tsx`: Static footer with icon-only settings, shortcuts, and about actions.
+- `SidebarProjectsList.tsx`: Main scrollable tree renderer for projects, root sessions, worktrees/groups, and empty/search states.
+- `SessionGroupSection.tsx`: Renders a single worktree/archived group, collapse/expand, folder subtree, and group-level controls.
+- `SessionNodeItem.tsx`: Renders one session row/tree node with inline metadata, menu actions, minimal/default variants, and nested children.
 - `ConfirmDialogs.tsx`: Shared confirm dialog wrappers for session delete and folder delete flows.
-- `sortableItems.tsx`: DnD sortable wrappers for project and group ordering with drag handles/overlays.
+- `sortableItems.tsx`: DnD sortable wrappers for project and group ordering plus project-row action affordances.
 - `sessionFolderDnd.tsx`: Folder/session DnD scope and wrappers for dropping/moving sessions into folders.
 
 ### Hooks
@@ -32,7 +37,7 @@
 - `hooks/useSessionGrouping.ts`: Builds grouped session structures and search text/filter helpers.
 - `hooks/useSessionSidebarSections.ts`: Composes final per-project sections and group search metadata for rendering.
 - `hooks/useProjectSessionSelection.ts`: Resolves active/current project-session selection logic and session-directory context.
-- `hooks/useGroupOrdering.ts`: Applies persisted/custom group order with stable fallback ordering.
+- `hooks/useGroupOrdering.ts`: Applies persisted/custom group order with stable fallback ordering; archived groups are reorderable.
 - `hooks/useArchivedAutoFolders.ts`: Maintains archived auto-folder structure and assignment behavior.
 - `hooks/useSidebarPersistence.ts`: Persists sidebar UI state (expanded/collapsed/pinned/group order/active session) to storage + desktop settings.
 - `hooks/useProjectRepoStatus.ts`: Tracks per-project git-repo state and root branch metadata.
@@ -43,4 +48,5 @@
 ### Types and utilities
 
 - `types.ts`: Shared sidebar types (`SessionNode`, `SessionGroup`, summary/search metadata).
-- `utils.tsx`: Shared sidebar utilities (path normalization, sorting, dedupe, archived scope keys, project relation checks, text highlight, labels).
+- `activitySections.ts`: Persisted top-section storage/helpers for the current `recent` session list.
+- `utils.tsx`: Shared sidebar utilities (path normalization, sorting, dedupe, archived scope keys, project relation checks, text highlight, labels, compact/default date formatting).