feat(web): redesign home page upload flow and add auth guard

Home page: after uploading an image, shows tool selector on the left
(quick actions + all 37 tools by category) with image preview on the
right. Stays on the main page — no popup overlay.

Auth: when AUTH_ENABLED=true, unauthenticated users are redirected to
/login. Default credentials admin/admin. When auth is disabled (dev
default), no redirect happens.

apps/web/src/App.tsx

@@ -1,22 +1,52 @@
-import { BrowserRouter, Routes, Route } from "react-router-dom";
+import { BrowserRouter, Routes, Route, Navigate, useLocation } from "react-router-dom";
 import { HomePage } from "./pages/home-page";
 import { LoginPage } from "./pages/login-page";
 import { ToolPage } from "./pages/tool-page";
 import { AutomatePage } from "./pages/automate-page";
 import { FullscreenGridPage } from "./pages/fullscreen-grid-page";
 import { KeyboardShortcutProvider } from "./components/common/keyboard-shortcut-provider";
+import { useAuth } from "./hooks/use-auth";
+
+function AuthGuard({ children }: { children: React.ReactNode }) {
+  const { loading, authEnabled, isAuthenticated } = useAuth();
+  const location = useLocation();
+
+  // Don't guard the login page itself
+  if (location.pathname === "/login") {
+    return <>{children}</>;
+  }
+
+  if (loading) {
+    return (
+      <div className="flex h-screen items-center justify-center bg-background text-foreground">
+        <div className="text-center space-y-3">
+          <div className="h-8 w-8 border-2 border-primary border-t-transparent rounded-full animate-spin mx-auto" />
+          <p className="text-sm text-muted-foreground">Loading...</p>
+        </div>
+      </div>
+    );
+  }
+
+  if (authEnabled && !isAuthenticated) {
+    return <Navigate to="/login" replace />;
+  }
+
+  return <>{children}</>;
+}
 
 export function App() {
   return (
     <BrowserRouter>
       <KeyboardShortcutProvider>
-        <Routes>
-          <Route path="/login" element={<LoginPage />} />
-          <Route path="/automate" element={<AutomatePage />} />
-          <Route path="/fullscreen" element={<FullscreenGridPage />} />
-          <Route path="/:toolId" element={<ToolPage />} />
-          <Route path="/" element={<HomePage />} />
-        </Routes>
+        <AuthGuard>
+          <Routes>
+            <Route path="/login" element={<LoginPage />} />
+            <Route path="/automate" element={<AutomatePage />} />
+            <Route path="/fullscreen" element={<FullscreenGridPage />} />
+            <Route path="/:toolId" element={<ToolPage />} />
+            <Route path="/" element={<HomePage />} />
+          </Routes>
+        </AuthGuard>
       </KeyboardShortcutProvider>
     </BrowserRouter>
   );