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.

tests/uptime-kuma/functional/test_spa_branding.py

@@ -42,9 +42,9 @@ def test_uptime_kuma_spa_has_branding(live_app):
 
     body = harness_http.assert_converges(_ready, f"GET {url}", max_wait=60, interval=3)
     lower = body.lower()
-    assert "uptime kuma" in lower or "kuma" in lower, (
-        f"Page body has no 'kuma' brand. Excerpt: {body[:200]!r}"
-    )
+    assert (
+        "uptime kuma" in lower or "kuma" in lower
+    ), f"Page body has no 'kuma' brand. Excerpt: {body[:200]!r}"
     # SPA-bundle markers: at least one of these reference paths should be present
     bundle_markers = ("/assets/", "/icon.svg", "favicon", "main.")
     present = [m for m in bundle_markers if m in body]