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

- Remove gosimple (absorbed into staticcheck in v2)
- Use default: none with explicit enable list
- Use exclusions.presets for standard exclusions
- Use exclusions.rules for SA1019 suppression

Validated against golangci-lint v2.11.4 schema.

Author: SoulKyu

.golangci.yml

@@ -1,17 +1,20 @@
 version: "2"
 
 linters:
+  default: none
   enable:
     - errcheck
     - govet
     - staticcheck
     - unused
-    - gosimple
     - ineffassign
   settings:
     govet:
       enable-all: false
   exclusions:
+    presets:
+      - std-error-handling
+      - common-false-positives
     rules:
       - linters:
           - staticcheck