style: repo-wide lint pass — make the lint gate green again

Push builds have been RED on the lint step since ~build 209 from accumulated
formatting drift. This is the mechanical cleanup: ruff format + ruff --fix
(UP038 isinstance unions, SIM105 contextlib.suppress, UP031 f-strings, SIM115
tempfile context manager), shfmt -i 2 -ci, nixpkgs-fmt/statix/deadnix (merged
attrsets, dropped unused lib args), yamllint, and shell quoting fixes in
tests/lasuite-docs/setup_custom_tests.sh. No behaviour changes intended;
lint: PASS, unit tests: 138 passed.

nix/modules/nightly-sweep.nix

@@ -29,7 +29,7 @@ in
     serviceConfig = {
       Type = "oneshot";
       # A full sweep across several recipes (each a cold deploy/test/teardown) is long; bound it.
-      TimeoutStartSec = "21600";  # 6h ceiling
+      TimeoutStartSec = "21600"; # 6h ceiling
       ExecStart = "${sweep}/bin/cc-ci-nightly-sweep";
     };
   };
@@ -39,7 +39,7 @@ in
     wantedBy = [ "timers.target" ];
     timerConfig = {
       OnCalendar = "*-*-* 03:00:00";
-      Persistent = true;   # catch up a missed nightly after downtime
+      Persistent = true; # catch up a missed nightly after downtime
       RandomizedDelaySec = "600";
     };
   };