chore: ruff auto-fixes — collapsible-else-if, if-stmt-min-max, dict.fromkeys (#23926)

PLR5501 (collapsible-else-if): 28 instances — else: if: → elif:
PLR1730 (if-stmt-min-max):   15 instances — if x<y: x=y → x=max(x,y)
C420   (dict.fromkeys):       2 instances — dictcomp → dict.fromkeys
PLR1704 (redefined-argument): 1 instance — reason → err_msg (shadow fix)
C414   (unnecessary-list):    1 instance — sorted(list(x)) → sorted(x)

28 files, -44 net lines. All mechanical, zero logic changes.
17,211 tests pass, zero regressions.

cron/jobs.py

@@ -1082,9 +1082,8 @@ def rewrite_skill_refs(
                         new_skills.append(target)
                 elif name in pruned_set:
                     dropped.append(name)
-                else:
-                    if name not in new_skills:
-                        new_skills.append(name)
+                elif name not in new_skills:
+                    new_skills.append(name)
 
             if not mapped and not dropped:
                 continue