T-1: initialize monorepo structure with backend and frontend scaffolds

Backend: Spring Boot 3.5.11 on Java 25, Maven with wrapper, hexagonal
architecture package layout (domain/application/adapter/config), health
endpoint with integration test. Originally planned for Spring Boot 4.0
but pivoted due to massive package reorganization in 4.0 (see addenda
in research and plan docs).

Frontend: Vue 3 scaffolded via create-vue with TypeScript, Vue Router,
Vitest, ESLint, Prettier. Pivoted from Svelte due to ecosystem maturity
concerns (broken router ecosystem for Svelte 5).

Also: extended .gitignore for Java/Maven and Node/Vue artifacts, updated
CLAUDE.md with tech stack, build commands, agent documentation sections,
and document integrity rule.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/router/index.ts

@@ -0,0 +1,23 @@
+import { createRouter, createWebHistory } from 'vue-router'
+import HomeView from '../views/HomeView.vue'
+
+const router = createRouter({
+  history: createWebHistory(import.meta.env.BASE_URL),
+  routes: [
+    {
+      path: '/',
+      name: 'home',
+      component: HomeView,
+    },
+    {
+      path: '/about',
+      name: 'about',
+      // route level code-splitting
+      // this generates a separate chunk (About.[hash].js) for this route
+      // which is lazy-loaded when the route is visited.
+      component: () => import('../views/AboutView.vue'),
+    },
+  ],
+})
+
+export default router