ci: bump golangci-lint v2.1 → v2.11 for Go 1.26 compat

golangci-lint v2.1 was built with Go 1.24 and panics when type-checking
Go 1.26 source files. Lint has been broken since Feb 16 when
actions/setup-go stable resolved to Go 1.26.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ysyneu

.github/workflows/lint.yml

@@ -20,4 +20,4 @@ jobs:
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v8
         with:
-          version: v2.1
+          version: v2.11