fix(lint): F821 undefined 'e' in test_scm_configured; shfmt/ruff auto-fixes

- test_scm_configured.py: remove reference to exception variable `e` outside
  its except block (F821); assert message doesn't need the code value
- shfmt auto-formatted install_steps.sh (spacing in write_env call)
- ruff auto-fixed one remaining issue
- 19/19 unit tests pass; lint PASS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_deps.py

@@ -122,7 +122,10 @@ def test_fallback_skips_warm_entries(tmp_path, monkeypatch):
     deps.write_run_state(mixed)
 
     raw = deps.load_run_state()
-    cold_raw = [e for e in (raw if isinstance(raw, list) else list(raw.values()))
-                if isinstance(e, dict) and not e.get("warm")]
+    cold_raw = [
+        e
+        for e in (raw if isinstance(raw, list) else list(raw.values()))
+        if isinstance(e, dict) and not e.get("warm")
+    ]
     assert len(cold_raw) == 1
     assert cold_raw[0]["recipe"] == "gitea"