fix: address three unresolved review comments in InitStep

- Use `with os.scandir(...)` context manager so the iterator is always
  closed even when `any()` short-circuits, preventing file-descriptor
  leaks in long-running workflow runs.
- Guard `os.chdir(prev_cwd)` in the `finally` block with a try/except
  so an `OSError` (e.g. directory deleted) doesn't bypass returning
  the captured `StepResult`.
- Reject non-string `script` values in `validate()` with a clear error
  message, rather than silently passing them through to become
  `--script True` at runtime.

Author: Copilot

src/specify_cli/workflows/steps/init/__init__.py

@@ -100,7 +100,8 @@ def execute(self, config: dict[str, Any], context: StepContext) -> StepResult:
         if targets_current_dir and not force:
             base = context.project_root or os.getcwd()
             try:
-                not_empty = any(os.scandir(base))
+                with os.scandir(base) as it:
+                    not_empty = any(it)
             except OSError:
                 not_empty = False
             if not_empty:
@@ -202,7 +203,10 @@ def _run_init(
         try:
             result = runner.invoke(app, argv, catch_exceptions=True)
         finally:
-            os.chdir(prev_cwd)
+            try:
+                os.chdir(prev_cwd)
+            except OSError:
+                pass
 
         stdout = result.output or ""
         # click >= 8.2 captures stderr separately; older versions mix it into
@@ -221,7 +225,12 @@ def _run_init(
     def validate(self, config: dict[str, Any]) -> list[str]:
         errors = super().validate(config)
         script = config.get("script")
-        if (
+        if script is not None and not isinstance(script, str):
+            errors.append(
+                f"Init step {config.get('id', '?')!r}: 'script' must be a string "
+                f"({' or '.join(repr(s) for s in VALID_SCRIPT_TYPES)})."
+            )
+        elif (
             isinstance(script, str)
             and "{{" not in script
             and script not in VALID_SCRIPT_TYPES