release: align the repo version with the shipped 0.2.1 and guard future tags (#219)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/web/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@prismshadow/penguin-web",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "private": true,
   "type": "module",
   "description": "PenguinHarness web frontend SPA: React + Vite + Tailwind CSS, rendering conversations streamed over the OmniMessage protocol, plus Agent configuration, model configuration, usage stats, and Traces.",