chore: update golangci-lint to v2.13.0

Migrate the deprecated gofumpt `extra-rules` to `extra.group-params`, as
the alias now also enables the new `clothe-returns` and `balance-calls`
rules. Disable SA4023, which hangs on go 1.27, see
https://github.com/golangci/golangci-lint/issues/6732.

Apply the resulting modernize fixes, mostly flattening embedded struct
literals and switching errors.As to errors.AsType.

Assisted-by: Claude:Opus 5

modules/setting/cron_test.go

@@ -30,9 +30,7 @@ EXTEND = true
 	assert.NoError(t, err)
 
 	extended := &Extended{
-		BaseStruct: BaseStruct{
-			Second: "queen of hearts",
-		},
+		Second: "queen of hearts",
 	}
 
 	_, err = getCronSettings(cfg, "test", extended)
@@ -71,15 +69,11 @@ THIRD = white rabbit
 	assert.NoError(t, err)
 
 	extended := &Extended2{
-		Extended: Extended{
-			BaseStruct: BaseStruct{
-				Enabled:    false,
-				RunAtStart: false,
-				Schedule:   "@every 72h",
-			},
-			Extend: false,
-		},
-		Third: "black rabbit",
+		Enabled:    false,
+		RunAtStart: false,
+		Schedule:   "@every 72h",
+		Extend:     false,
+		Third:      "black rabbit",
 	}
 
 	_, err = getCronSettings(cfg, "test", extended)