fix: open for write only, not read.

src/plan/path.py

@@ -16,7 +16,7 @@ def open(plan: Path):
 
     if not plan.exists():
         plan.touch()
-        with plan.open("rw") as f:
+        with plan.open("w") as f:
             f.write(default())
     editor = os.getenv("EDITOR", "nvim")
     subprocess.run([editor, str(plan)])