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/views/GitView.tsx

@@ -433,6 +433,7 @@ export const GitView: React.FC = () => {
     return isActionTab(stored) ? stored : 'commit';
   });
   const [remotes, setRemotes] = React.useState<GitRemote[]>([]);
+  const [removingRemoteName, setRemovingRemoteName] = React.useState<string | null>(null);
   const [branchOperation, setBranchOperation] = React.useState<BranchOperation>(null);
   const [operationLogs, setOperationLogs] = React.useState<OperationLogEntry[]>([]);
   const [conflictDialogOpen, setConflictDialogOpen] = React.useState(false);
@@ -585,14 +586,23 @@ export const GitView: React.FC = () => {
     git.getRemoteUrl(currentDirectory).then(setRemoteUrl).catch(() => setRemoteUrl(null));
   }, [currentDirectory, git]);
 
-  React.useEffect(() => {
+  const refreshRemotes = React.useCallback(async () => {
     if (!currentDirectory || !git?.getRemotes) {
       setRemotes([]);
       return;
     }
-    git.getRemotes(currentDirectory).then(setRemotes).catch(() => setRemotes([]));
+    try {
+      const remoteList = await git.getRemotes(currentDirectory);
+      setRemotes(remoteList);
+    } catch {
+      setRemotes([]);
+    }
   }, [currentDirectory, git]);
 
+  React.useEffect(() => {
+    void refreshRemotes();
+  }, [refreshRemotes]);
+
   React.useEffect(() => {
     if (!settingsGitmojiEnabled) {
       setGitmojiEmojis([]);
@@ -825,6 +835,35 @@ export const GitView: React.FC = () => {
     }
   };
 
+  const handleRemoveRemote = React.useCallback(async (remote: GitRemote) => {
+    if (!currentDirectory) return;
+
+    const remoteName = remote.name.trim();
+    if (!remoteName) {
+      toast.error('Remote name is required');
+      return;
+    }
+    if (remoteName === 'origin') {
+      toast.error('Cannot remove origin remote');
+      return;
+    }
+
+    setRemovingRemoteName(remoteName);
+    try {
+      await git.removeRemote(currentDirectory, { remote: remoteName });
+      toast.success(`Removed ${remoteName} remote`);
+      await Promise.all([
+        refreshStatusAndBranches(false),
+        refreshRemotes(),
+      ]);
+    } catch (error) {
+      const message = error instanceof Error ? error.message : `Failed to remove ${remoteName}`;
+      toast.error(message);
+    } finally {
+      setRemovingRemoteName(null);
+    }
+  }, [currentDirectory, git, refreshRemotes, refreshStatusAndBranches]);
+
   const handleCommit = async (options: { pushAfter?: boolean } = {}) => {
     if (!currentDirectory) return;
     if (!commitMessage.trim()) {
@@ -1254,11 +1293,20 @@ export const GitView: React.FC = () => {
         }
 
         const insertBeforeIndex = log.all.findIndex((entry) => !branchHashes.has(entry.hash));
-        if (insertBeforeIndex <= 0) {
+        if (insertBeforeIndex === 0) {
           setHistoryBranchDivider(null);
           return;
         }
 
+        if (insertBeforeIndex === -1) {
+          setHistoryBranchDivider({
+            insertBeforeIndex: log.all.length,
+            branchName: currentBranch,
+            direction: 'up',
+          });
+          return;
+        }
+
         setHistoryBranchDivider({
           insertBeforeIndex,
           branchName: currentBranch,
@@ -1806,6 +1854,8 @@ export const GitView: React.FC = () => {
         onFetch={(remote) => handleSyncAction('fetch', remote)}
         onPull={(remote) => handleSyncAction('pull', remote)}
         onPush={() => handleSyncAction('push')}
+        onRemoveRemote={handleRemoveRemote}
+        removingRemoteName={removingRemoteName}
         onCheckoutBranch={handleCheckoutBranch}
         onCreateBranch={handleCreateBranch}
         onRenameBranch={handleRenameBranch}
@@ -1861,7 +1911,6 @@ export const GitView: React.FC = () => {
                   {(changeEntries?.length ?? 0) > 0 ? (
                     <>
                       <ChangesSection
-                        variant="plain"
                         maxListHeightClassName="max-h-[40vh]"
                         changeEntries={changeEntries}
                         onVisiblePathsChange={setVisibleChangePaths}
@@ -1887,7 +1936,6 @@ export const GitView: React.FC = () => {
                       />
 
                       <CommitSection
-                        variant="plain"
                         selectedCount={selectedCount}
                         commitMessage={commitMessage}
                         onCommitMessageChange={setCommitMessage}
@@ -1945,7 +1993,6 @@ export const GitView: React.FC = () => {
                 <div className="space-y-4">
                   {integrateCommitsProps ? (
                     <IntegrateCommitsSection
-                      variant="plain"
                       repoRoot={integrateCommitsProps.repoRoot}
                       sourceBranch={integrateCommitsProps.sourceBranch}
                       worktreeMetadata={integrateCommitsProps.worktreeMetadata}
@@ -1974,7 +2021,6 @@ export const GitView: React.FC = () => {
                 <div className="space-y-4">
                   {pullRequestProps ? (
                     <PullRequestSection
-                      variant="plain"
                       directory={pullRequestProps.directory}
                       branch={pullRequestProps.branch}
                       baseBranch={baseBranch}