refactor(site): rename <404Page /> to <NotFoundPage /> (#27731)

The component was already named `NotFoundPage`, but it lived under
`pages/404Page/404Page.tsx`. Rename the directory and file to match the
component name, and update the lazy import and organization settings
import paths.

site/src/modules/management/OrganizationSettingsLayout.tsx

@@ -18,7 +18,7 @@ import {
 	canViewOrganization,
 	type OrganizationPermissions,
 } from "#/modules/permissions/organizations";
-import NotFoundPage from "#/pages/404Page/404Page";
+import NotFoundPage from "#/pages/NotFoundPage/NotFoundPage";
 
 export const OrganizationSettingsContext = createContext<
 	OrganizationSettingsValue | undefined

site/src/pages/NotFoundPage/NotFoundPage.stories.tsx

@@ -1,5 +1,5 @@
 import type { Meta, StoryObj } from "@storybook/react-vite";
-import NotFoundPage from "./404Page";
+import NotFoundPage from "./NotFoundPage";
 
 const meta: Meta<typeof NotFoundPage> = {
 	title: "components/NotFoundPage",

site/src/router.tsx

@@ -32,7 +32,7 @@ import WorkspacesPage from "./pages/WorkspacesPage/WorkspacesPage";
 // Lazy load pages
 // - Pages that are secondary, not in the main navigation or not usually accessed
 // - Pages that use heavy dependencies like charts or time libraries
-const NotFoundPage = lazy(() => import("./pages/404Page/404Page"));
+const NotFoundPage = lazy(() => import("./pages/NotFoundPage/NotFoundPage"));
 const DeploymentSettingsLayout = lazy(
 	() => import("./modules/management/DeploymentSettingsLayout"),
 );