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>

README.md

@@ -36,7 +36,7 @@ A privacy-focused, self-hostable web app for event announcements and RSVPs. An a
 | Layer        | Technology                               |
 |--------------|------------------------------------------|
 | Backend      | Java (latest LTS), Spring Boot, Maven    |
-| Frontend     | Svelte, Vite                             |
+| Frontend     | Vue 3, Vite, TypeScript                  |
 | Database     | PostgreSQL (external, not bundled)        |
 | Architecture | SPA + RESTful API, hexagonal/onion backend |
 | Deployment   | Single Docker container                  |
@@ -104,7 +104,7 @@ If you use the Unsplash header image feature, mount a persistent volume for stor
 ### Prerequisites
 
 - Java (latest LTS) + Maven
-- Node.js + npm
+- Node.js (latest LTS) + npm
 - PostgreSQL (or Docker for Testcontainers)
 
 ### Project structure
@@ -112,7 +112,7 @@ If you use the Unsplash header image feature, mount a persistent volume for stor
 ```
 fete/
 ├── backend/      # Spring Boot application (Maven)
-├── frontend/     # Svelte SPA (Vite)
+├── frontend/     # Vue 3 SPA (Vite, TypeScript)
 ├── spec/         # User stories, personas, implementation phases
 ├── Dockerfile    # Multi-stage build for production
 └── CLAUDE.md     # Project statutes and AI agent instructions