chore: release v0.12.1

Bump root/backend/frontend to 0.12.1 and move the CHANGELOG notes under a dated
0.12.1 heading (centered wallet-sync stepper, timeline record history, and the
landing-page globe deferral). Adds the radix-ui dependency pulled in by the
Origin UI stepper/timeline primitives.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "frontend",
-  "version": "0.12.0",
+  "version": "0.12.1",
   "private": true,
   "scripts": {
     "dev": "next dev",
@@ -52,6 +52,7 @@
     "nanoid": "^5.1.11",
     "next": "16.2.6",
     "next-themes": "^0.4.6",
+    "radix-ui": "^1.6.2",
     "react": "19.2.4",
     "react-day-picker": "^10.0.1",
     "react-dom": "19.2.4",