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/eslint.config.ts

@@ -0,0 +1,32 @@
+import { globalIgnores } from 'eslint/config'
+import { defineConfigWithVueTs, vueTsConfigs } from '@vue/eslint-config-typescript'
+import pluginVue from 'eslint-plugin-vue'
+import pluginVitest from '@vitest/eslint-plugin'
+import pluginOxlint from 'eslint-plugin-oxlint'
+import skipFormatting from 'eslint-config-prettier/flat'
+
+// To allow more languages other than `ts` in `.vue` files, uncomment the following lines:
+// import { configureVueProject } from '@vue/eslint-config-typescript'
+// configureVueProject({ scriptLangs: ['ts', 'tsx'] })
+// More info at https://github.com/vuejs/eslint-config-typescript/#advanced-setup
+
+export default defineConfigWithVueTs(
+  {
+    name: 'app/files-to-lint',
+    files: ['**/*.{vue,ts,mts,tsx}'],
+  },
+
+  globalIgnores(['**/dist/**', '**/dist-ssr/**', '**/coverage/**']),
+
+  ...pluginVue.configs['flat/essential'],
+  vueTsConfigs.recommended,
+
+  {
+    ...pluginVitest.configs.recommended,
+    files: ['src/**/__tests__/*'],
+  },
+
+  ...pluginOxlint.buildFromOxlintConfigFile('.oxlintrc.json'),
+
+  skipFormatting,
+)