fix(ci): migrate golangci-lint config to v2 schema

v2 renames: linters-settings → linters.settings, issues.exclude-rules →
issues.exclude, removes run.go field.

Author: SoulKyu

.golangci.yml

@@ -8,16 +8,12 @@ linters:
     - unused
     - gosimple
     - ineffassign
-
-linters-settings:
-  govet:
-    enable-all: false
+  settings:
+    govet:
+      enable-all: false
 
 issues:
-  exclude-rules:
+  exclude:
     - linters:
         - staticcheck
       text: "SA1019"
-
-run:
-  go: "1.25"