feat: v0.12.0 — fix streaming tool UI persistence, file tree UX improvements, unify icon library

Streaming tool UI fix (ChatView.tsx):
- Add toolUsesRef/toolResultsRef to reliably track tool data across closures
- Serialize tool_use/tool_result into JSON content-blocks array when building
  assistant message after stream ends, matching backend storage format
- MessageItem.parseToolBlocks() now renders tool UI from history messages
- Clean up refs in finally block and timeout auto-retry path

File tree UX (FileTree.tsx, file-tree.tsx):
- Remove folder path header from right panel, merge search + refresh into one row
- Remove file icon spacer (size-5) so file icons align flush with search box
- Change folder icon color from blue to muted-foreground

Chat list panel (ChatListPanel.tsx):
- Folder header: expanded uses FolderOpenIcon, collapsed uses Folder01Icon
- Add tooltip showing full working directory path on folder hover
- Double-click folder header opens in system file manager

Title bar folder name (chat/[id]/page.tsx):
- Add tooltip with full path on project name hover
- Click opens folder in Finder/Explorer via Electron IPC or API fallback

Open folder support:
- electron/main.ts: add shell:open-path IPC handler via shell.openPath
- electron/preload.ts: expose electronAPI.shell.openPath to renderer
- api/files/open/route.ts: fallback API route using open/explorer/xdg-open

Unify icon library — migrate app-level components from Lucide to Hugeicons:
- file-tree.tsx: folder, file, chevron, plus icons
- tool-actions-group.tsx: chevron expand icon
- MessageItem.tsx: copy, check, expand/collapse icons
- MessageInput.tsx: stop button (SquareIcon → StopIcon)
- FileCard.tsx: file icon
- ImageLightbox.tsx: left/right navigation arrows
- InstallWizard.tsx: status icons (check, x, minus, loader, circle, copy, download)
- Keep Lucide in ui/ and ai-elements/ base layers (shadcn standard)

src/components/ai-elements/file-tree.tsx

@@ -8,13 +8,14 @@ import {
   CollapsibleTrigger,
 } from "@/components/ui/collapsible";
 import { cn } from "@/lib/utils";
+import { HugeiconsIcon } from "@hugeicons/react";
 import {
-  ChevronRightIcon,
-  FileIcon,
-  FolderIcon,
+  Folder01Icon,
   FolderOpenIcon,
-  PlusIcon,
-} from "lucide-react";
+  File01Icon,
+  ArrowRight01Icon,
+  PlusSignIcon,
+} from "@hugeicons/core-free-icons";
 import {
   createContext,
   useCallback,
@@ -154,7 +155,8 @@ export const FileTreeFolder = ({
                 className="shrink-0 rounded p-0.5 hover:bg-muted"
                 onClick={(e) => e.stopPropagation()}
               >
-                <ChevronRightIcon
+                <HugeiconsIcon
+                  icon={ArrowRight01Icon}
                   className={cn(
                     "size-4 text-muted-foreground transition-transform",
                     isExpanded && "rotate-90"
@@ -164,9 +166,9 @@ export const FileTreeFolder = ({
             </CollapsibleTrigger>
             <FileTreeIcon>
               {isExpanded ? (
-                <FolderOpenIcon className="size-4 text-blue-500" />
+                <HugeiconsIcon icon={FolderOpenIcon} className="size-4 text-muted-foreground" />
               ) : (
-                <FolderIcon className="size-4 text-blue-500" />
+                <HugeiconsIcon icon={Folder01Icon} className="size-4 text-muted-foreground" />
               )}
             </FileTreeIcon>
             <FileTreeName>{name}</FileTreeName>
@@ -246,10 +248,8 @@ export const FileTreeFile = ({
       >
         {children ?? (
           <>
-            {/* Spacer matching folder chevron button (size-4 icon + p-0.5 padding) */}
-            <span className="size-5 shrink-0" />
             <FileTreeIcon>
-              {icon ?? <FileIcon className="size-4 text-muted-foreground" />}
+              {icon ?? <HugeiconsIcon icon={File01Icon} className="size-4 text-muted-foreground" />}
             </FileTreeIcon>
             <FileTreeName>{name}</FileTreeName>
             {onAdd && (
@@ -259,7 +259,7 @@ export const FileTreeFile = ({
                 onClick={handleAdd}
                 title="Add to chat"
               >
-                <PlusIcon className="size-3 text-muted-foreground" />
+                <HugeiconsIcon icon={PlusSignIcon} className="size-3 text-muted-foreground" />
               </button>
             )}
           </>

src/components/ai-elements/tool-actions-group.tsx

@@ -13,8 +13,8 @@ import {
   Loading02Icon,
   CheckmarkCircle02Icon,
   CancelCircleIcon,
+  ArrowRight01Icon,
 } from "@hugeicons/core-free-icons";
-import { ChevronRightIcon } from 'lucide-react';
 import { cn } from '@/lib/utils';
 
 // ---------------------------------------------------------------------------
@@ -229,7 +229,8 @@ export function ToolActionsGroup({
         onClick={handleToggle}
         className="flex w-full items-center gap-2 py-1 text-xs rounded-sm hover:bg-muted/30 transition-colors"
       >
-        <ChevronRightIcon
+        <HugeiconsIcon
+          icon={ArrowRight01Icon}
           className={cn(
             "h-3 w-3 shrink-0 text-muted-foreground/60 transition-transform duration-200",
             expanded && "rotate-90"