scaffold blog_portal vue 3 + pinia + cypress frontend

Mirrors youngstartup/frontend/startups_portal scaffolding:
Vite, Vue 3 (composition API + script setup), TypeScript strict,
Pinia, Vue Router 5, oxlint + eslint + oxfmt, and Cypress with
db:reset / db:seed tasks. Views and the auth store are stubs
filled in by the next branches; routes and the header chrome
are wired so the build passes.

frontend/blog_portal/src/App.vue

@@ -0,0 +1,119 @@
+<script setup lang="ts">
+import AppHeader from "@/components/AppHeader.vue";
+</script>
+
+<template>
+  <div class="app">
+    <AppHeader />
+    <main class="app-main">
+      <router-view />
+    </main>
+  </div>
+</template>
+
+<style scoped>
+.app {
+  display: flex;
+  flex-direction: column;
+  min-height: 100vh;
+}
+
+.app-main {
+  flex: 1;
+  min-width: 0;
+  padding: 24px;
+  max-width: 960px;
+  width: 100%;
+  margin: 0 auto;
+}
+</style>
+
+<style>
+:root {
+  font-family:
+    Inter,
+    -apple-system,
+    BlinkMacSystemFont,
+    "Segoe UI",
+    Roboto,
+    sans-serif;
+  --color-text: #0a0a0a;
+  --color-secondary: #6b6b6b;
+  --color-border: #e5e5e5;
+  --color-accent: #0062ff;
+  --color-bg: #fff;
+  --color-button: #000;
+  --color-button-hover: #222;
+}
+
+body {
+  margin: 0;
+  background: var(--color-bg);
+  color: var(--color-text);
+}
+
+* {
+  box-sizing: border-box;
+}
+
+a {
+  color: var(--color-accent);
+  text-decoration: none;
+}
+
+a:hover {
+  text-decoration: underline;
+}
+
+input,
+button,
+select,
+textarea {
+  font: inherit;
+}
+
+input[type="text"],
+input[type="email"],
+input[type="password"],
+input[type="search"] {
+  height: 36px;
+  padding: 0 12px;
+  border: 1px solid var(--color-border);
+  border-radius: 6px;
+  background: #fff;
+  color: var(--color-text);
+}
+
+input:focus {
+  outline: none;
+  border-color: #000;
+}
+
+button {
+  height: 36px;
+  padding: 0 16px;
+  border: 1px solid var(--color-border);
+  border-radius: 6px;
+  background: var(--color-button);
+  color: #fff;
+  cursor: pointer;
+}
+
+button:hover:not(:disabled) {
+  background: var(--color-button-hover);
+}
+
+button:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+button.secondary {
+  background: #fff;
+  color: var(--color-text);
+}
+
+button.secondary:hover:not(:disabled) {
+  background: #f5f5f5;
+}
+</style>