feat: implement Files page with persistent storage and version tracking

Three-panel file manager (nav, list, details) modeled after Stirling-PDF.
- Backend: user_files table, /api/v1/files/* CRUD routes, file storage
  helpers, thumbnail generation via Sharp, recursive CTE version chains
- Frontend: FilesNav, FileList, FileDetails, FileUploadArea components,
  Zustand store, mobile layout with bottom sheet
- Integration: tool-factory auto-saves results as new versions when
  fileId is provided, "Open File" loads file into tool processing flow
- Search, bulk select/delete/download, version badges, tool chain tags

apps/web/src/components/layout/sidebar.tsx

@@ -1,14 +1,7 @@
+import type { LucideIcon } from "lucide-react";
+import { FolderOpen, Grid3x3, HelpCircle, LayoutGrid, Settings, Workflow } from "lucide-react";
 import { Link, useLocation } from "react-router-dom";
 import { cn } from "@/lib/utils";
-import {
-  LayoutGrid,
-  Workflow,
-  HelpCircle,
-  Settings,
-  Grid3x3,
-  FolderOpen,
-} from "lucide-react";
-import type { LucideIcon } from "lucide-react";
 
 interface SidebarItem {
   icon: LucideIcon;
@@ -45,7 +38,7 @@ export function Sidebar({ onSettingsClick, onHelpClick, expanded = false }: Side
           "flex items-center gap-3 px-4 py-2.5 rounded-lg cursor-pointer transition-colors",
           isActive
             ? "bg-primary text-primary-foreground"
-            : "text-muted-foreground hover:bg-muted hover:text-foreground"
+            : "text-muted-foreground hover:bg-muted hover:text-foreground",
         )}
       >
         <item.icon className="h-5 w-5" />
@@ -57,7 +50,7 @@ export function Sidebar({ onSettingsClick, onHelpClick, expanded = false }: Side
           "flex flex-col items-center gap-1 p-2 rounded-lg cursor-pointer transition-colors",
           isActive
             ? "bg-primary text-primary-foreground"
-            : "text-muted-foreground hover:bg-muted hover:text-foreground"
+            : "text-muted-foreground hover:bg-muted hover:text-foreground",
         )}
       >
         <item.icon className="h-6 w-6" />
@@ -89,9 +82,7 @@ export function Sidebar({ onSettingsClick, onHelpClick, expanded = false }: Side
   if (expanded) {
     return (
       <div className="flex flex-col p-3 gap-1">
-        {topItems.map((item) =>
-          renderItem(item, location.pathname === item.href)
-        )}
+        {topItems.map((item) => renderItem(item, location.pathname === item.href))}
         <div className="border-t border-border my-2" />
         {bottomItems.map((item) => renderItem(item, false))}
       </div>
@@ -101,9 +92,7 @@ export function Sidebar({ onSettingsClick, onHelpClick, expanded = false }: Side
   return (
     <aside className="flex flex-col items-center w-16 bg-sidebar border-r border-border py-3 gap-1 shrink-0">
       <div className="flex flex-col gap-1 flex-1">
-        {topItems.map((item) =>
-          renderItem(item, location.pathname === item.href)
-        )}
+        {topItems.map((item) => renderItem(item, location.pathname === item.href))}
       </div>
       <div className="border-t border-border w-10 my-2" />
       <div className="flex flex-col gap-1">