harden: remove shell parameter from run_command() (#3716)

run_command() enforces a list[str] argv contract, so a shell parameter
served no purpose beyond keeping an unnecessary shell-injection surface
that a future refactor could re-enable. Remove the parameter (and its
now-dead ValueError guard) so shell=False is the only possible behavior.

Assisted-by: GitHub Copilot (model: Claude Opus 4.8, autonomous)

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 74a1bd02-f6cd-412a-b5a8-a7767a5e058d

src/specify_cli/_utils.py

@@ -69,21 +69,14 @@ def run_command(
     cmd: list[str],
     check_return: bool = True,
     capture: bool = False,
-    shell: bool = False,
 ) -> str | None:
     """Run a command without invoking a shell and optionally capture output.
 
-    The ``shell`` parameter is kept in the signature so existing keyword
-    callers (and the re-export from ``specify_cli``) don't raise ``TypeError``,
-    but only the default ``shell=False`` is honoured. ``shell=True`` is
-    rejected with ``ValueError`` rather than silently ignored, so the
-    unsupported mode fails loudly instead of running with a different meaning.
+    Commands are always executed with ``shell=False`` and must be passed as an
+    argv ``list[str]``. There is deliberately no ``shell`` parameter: the
+    argv-list contract makes shell interpolation impossible by construction, so
+    the shell-injection surface cannot be re-enabled at a call site.
     """
-    if shell:
-        raise ValueError(
-            "run_command() does not support shell=True; pass argv as a list"
-        )
-
     try:
         if capture:
             result = subprocess.run(cmd, check=check_return, capture_output=True, text=True)