feat(web): migrate application shell to TanStack Start

- replace the legacy client-only Vite bootstrap with TanStack Router routes, Start SSR, and Nitro output

- compose the reusable layout, navigation, appearance, chats, and notifications blocks with application-owned data

- persist UI preferences through server functions and initialize theme, sidebar, and breakpoint state before hydration

- add React Query, hotkey, toaster, and responsive dashboard integration

- add application-owned Lingui configuration and catalogs, mount the runtime provider, and lazily enable I18nDevtool in development

- remove superseded HTML, main entry, theme provider, and application ESLint configuration

apps/web/src/server/ui-state.functions.ts

@@ -0,0 +1,18 @@
+import { createServerFn } from "@tanstack/react-start"
+import { isUiStateUpdate } from "@workspace/blocks/appearance"
+import { readUiState, writeUiState } from "./ui-state.server"
+
+export const getUiState = createServerFn({ method: "GET" }).handler(() => {
+  return readUiState()
+})
+
+export const setUiState = createServerFn({ method: "POST" })
+  .validator((value: unknown) => {
+    if (!isUiStateUpdate(value)) {
+      throw new Error("Invalid UI state update")
+    }
+    return value
+  })
+  .handler(({ data }) => {
+    writeUiState(data.key, data.value)
+  })

apps/web/src/server/ui-state.server.ts

@@ -0,0 +1,39 @@
+import "@tanstack/react-start/server-only"
+import { getCookie, setCookie } from "@tanstack/react-start/server"
+import {
+  type UiState,
+  type UiStateKey,
+  uiStateDefinitions,
+} from "@workspace/blocks/appearance"
+
+const LEGACY_THEME_COOKIE = "simple-shop-admin-theme"
+
+export function readUiState(): UiState {
+  return {
+    "main-compacted": uiStateDefinitions["main-compacted"].parse(
+      getCookie(uiStateDefinitions["main-compacted"].cookie)
+    ),
+    "sidebar-collapsed": uiStateDefinitions["sidebar-collapsed"].parse(
+      getCookie(uiStateDefinitions["sidebar-collapsed"].cookie)
+    ),
+    "theme-mode": uiStateDefinitions["theme-mode"].parse(
+      getCookie(uiStateDefinitions["theme-mode"].cookie) ??
+        getCookie(LEGACY_THEME_COOKIE)
+    ),
+    "theme-light": uiStateDefinitions["theme-light"].parse(
+      getCookie(uiStateDefinitions["theme-light"].cookie)
+    ),
+    "theme-dark": uiStateDefinitions["theme-dark"].parse(
+      getCookie(uiStateDefinitions["theme-dark"].cookie)
+    ),
+  }
+}
+
+export function writeUiState<K extends UiStateKey>(key: K, value: UiState[K]) {
+  const definition = uiStateDefinitions[key]
+  setCookie(definition.cookie, definition.serialize(value), {
+    path: "/",
+    sameSite: "lax",
+    maxAge: 60 * 60 * 24 * 365,
+  })
+}