feat(worktree): onboard creator by default in worktree_prepare.sh (Issue #68)

tests/data/skill_code_blocks.json

@@ -91,7 +91,7 @@
    "start": 202,
    "end": 206,
    "lang": "bash",
-   "sha": "38836d31bf38",
+   "sha": "8bfabafb0328",
    "class": "c",
    "kind": "invocation",
    "evidence": [