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/views/AboutView.vue

@@ -0,0 +1,15 @@
+<template>
+  <div class="about">
+    <h1>This is an about page</h1>
+  </div>
+</template>
+
+<style>
+@media (min-width: 1024px) {
+  .about {
+    min-height: 100vh;
+    display: flex;
+    align-items: center;
+  }
+}
+</style>

frontend/src/views/HomeView.vue

@@ -0,0 +1,9 @@
+<script setup lang="ts">
+import TheWelcome from '../components/TheWelcome.vue'
+</script>
+
+<template>
+  <main>
+    <TheWelcome />
+  </main>
+</template>