fix: trigger preview-create on ready_for_review

PRs created as draft (or by automation tokens that suppress workflow
triggers) never ran preview-create because the workflow only listened
for opened/synchronize. Adding ready_for_review as a trigger ensures
the preview repo gets created when a draft PR is marked ready.

Also makes preview-create.ts idempotent by catching 422 (repo already
exists) so it's safe if both opened and ready_for_review fire.

Made-with: Cursor

package.json

@@ -3,9 +3,9 @@
   "version": "0.0.194",
   "type": "module",
   "bin": {
-    "pullfrog": "./dist/cli.mjs",
+    "pullfrog": "dist/cli.mjs",
-    "pullfrog-dev": "./dist/cli.mjs",
+    "pullfrog-dev": "dist/cli.mjs",
-    "pf": "./dist/cli.mjs"
+    "pf": "dist/cli.mjs"
   },
   "files": [
     "dist/"