M0: Vue 3 + TypeScript frontend — auth views + authed board shell

- Vite + Vue 3.5 + Pinia + vue-router + Tailwind (brand accent #F5C518),
  dark-mode aware, deterministic package-lock.json for `npm ci`.
- Session store (fetchMe/login/register/logout) over a credentials:'include'
  fetch client; router guards (requiresAuth / guestOnly) with lazy /me resolve.
- BaseButton + BaseInput primitives (focus rings, loading, error states).
- LoginView, RegisterView, and an authed BoardView shell with an empty state
  for the M1 masonry board — all at v1 polish (rule 24).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

frontend/package.json

@@ -0,0 +1,25 @@
+{
+  "name": "thoughtsync-frontend",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vue-tsc --noEmit && vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "pinia": "^2.2.0",
+    "vue": "^3.5.0",
+    "vue-router": "^4.4.0"
+  },
+  "devDependencies": {
+    "@vitejs/plugin-vue": "^5.1.0",
+    "autoprefixer": "^10.4.0",
+    "postcss": "^8.4.0",
+    "tailwindcss": "^3.4.0",
+    "typescript": "~5.5.0",
+    "vite": "^5.4.0",
+    "vue-tsc": "^2.1.0"
+  }
+}