feat: duplicate your own recipe

The fork endpoint already had no "isn't yours" check, so this is a
UI-only change: ForkRecipeButton takes a variant prop ("fork" for
others' recipes, "duplicate" for your own) that swaps icon/label/toast
copy, and now renders unconditionally instead of only for non-owners.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "epicure",
-  "version": "0.19.0",
+  "version": "0.20.0",
   "private": true,
   "scripts": {
     "dev": "pnpm --filter web dev",