Add neo-brutalist landing page

Title 'Sis' in nb-font-heading1, tagline 'For chores and stuff'
Warm cream background, centered nb-box layout

frontend/public/style.css

@@ -2,6 +2,7 @@
 
 body {
   min-height: 100vh;
+  background: #fff9e6;
 }
 
 #app {

frontend/src/components/App.ts

@@ -1,34 +1,15 @@
 import m, { Vnode } from "mithril";
 
-import { checkHealth } from "../api";
-
 interface AppAttrs {}
 
-interface AppState {
-  health: string;
-}
+interface AppState {}
 
 export const App: m.Component<AppAttrs, AppState> = {
-  oninit(vnode: Vnode<AppAttrs, AppState>) {
-    vnode.state.health = "loading...";
-    checkHealth()
-      .then((msg) => {
-        vnode.state.health = msg;
-        m.redraw();
-      })
-      .catch((err) => {
-        vnode.state.health = "error: " + String(err);
-        m.redraw();
-      });
-  },
-
-  view(vnode: Vnode<AppAttrs, AppState>) {
-    return m("main.container", { style: { maxWidth: "720px", margin: "2rem auto" } }, [
-      m("h1", "Sis"),
-      m("p", "Shared household chore tracker."),
-      m("p", [
-        m("strong", "API status: "),
-        m("span", vnode.state.health),
+  view(_vnode: Vnode<AppAttrs, AppState>) {
+    return m(".nb-container", { style: { maxWidth: "640px", margin: "0 auto" } }, [
+      m(".nb-box", { style: { marginTop: "4rem", textAlign: "center", padding: "3rem 2rem" } }, [
+        m("h1", { class: "nb-font-heading1" }, "Sis"),
+        m("p", { class: "nb-font-heading2", style: { marginTop: "1rem", opacity: "0.7" } }, "For chores and stuff"),
       ]),
     ]);
   },