fix(workflows): fail gate step loudly on a malformed 'options' (#3595)

`GateStep.validate` rejects a non-list (or empty) `options` and requires
every option to be a string, but the engine does not auto-validate before
`execute`. On an unvalidated run a scalar/dict/None `options` reached
`_prompt` and crashed the whole workflow with a raw `TypeError`
(`enumerate`/`len` on a non-iterable) or `KeyError` (indexing a dict); an
empty list spun `_prompt`'s input loop forever; a non-string option crashed
the reject check at `choice.lower()` with `AttributeError`.

Guard `execute` to FAIL the step cleanly instead, before the non-TTY
PAUSE short-circuit so the error surfaces in CI too rather than pausing
and only crashing later on interactive resume. Mirrors the switch 'cases'
and command 'input' unvalidated-execute guards.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -43,6 +43,35 @@ class GateStep(StepBase):
         options = config.get("options", ["approve", "reject"])
         on_reject = config.get("on_reject", "abort")
 
+        # ``validate`` rejects a non-list (or empty) ``options``, and requires
+        # every option to be a string, but the engine does not auto-validate
+        # before ``execute``. An unvalidated run with a scalar/dict/None
+        # ``options`` would otherwise reach ``_prompt`` and crash the whole run
+        # with a raw ``TypeError`` (``enumerate``/``len`` on a non-iterable) or
+        # ``KeyError`` (indexing a dict); a non-string option would crash at the
+        # ``choice.lower()`` reject check with ``AttributeError``. Fail this step
+        # loudly instead — mirroring the switch 'cases' and command 'input'
+        # guards. Checked before the non-TTY short-circuit so the error surfaces
+        # in CI too, rather than PAUSING and crashing later on interactive resume.
+        if (
+            not isinstance(options, list)
+            or not options
+            or not all(isinstance(o, str) for o in options)
+        ):
+            return StepResult(
+                status=StepStatus.FAILED,
+                error=(
+                    f"Gate step {config.get('id', '?')!r}: 'options' must be a "
+                    f"non-empty list of strings, got {type(options).__name__}."
+                ),
+                output={
+                    "message": message,
+                    "options": options,
+                    "on_reject": on_reject,
+                    "choice": None,
+                },
+            )
+
         show_file = config.get("show_file")
         if isinstance(show_file, str) and "{{" in show_file:
             show_file = evaluate_expression(show_file, context)