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/tsconfig.vitest.json

@@ -0,0 +1,19 @@
+{
+  "extends": "./tsconfig.app.json",
+
+  // Override to include only test files and clear exclusions.
+  // Application code imported in tests is automatically included via module resolution.
+  "include": ["src/**/__tests__/*", "env.d.ts"],
+  "exclude": [],
+
+  "compilerOptions": {
+    // Vitest runs in a different environment than the application code.
+    // Adjust lib and types accordingly.
+    "lib": [],
+    "types": ["node", "jsdom"],
+
+    // `vue-tsc --build` produces a .tsbuildinfo file for incremental type-checking.
+    // Specified here to keep it out of the root directory.
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.vitest.tsbuildinfo"
+  }
+}