chore: Bump golangci-lint to v2.11.1

[devin-ai-integration]

Summary

Bumps golangci-lint from v1.48.0 to v2.11.1 in the Makefile and fixes two lint issues surfaced by the new version's stricter/changed defaults:

• consul_impl.go: Updated //nolint:stylecheck → //nolint:staticcheck because stylecheck was merged into staticcheck in golangci-lint v2 (the old directive was flagged as an unknown linter by nolintlint). The capitalized error string in fmt.Errorf("Consul transaction failed: ...") is intentional.
• consul_test.go: Added //nolint:errcheck to defer store.Close() in test cleanup code, since errcheck is now enabled by default in v2.

Part of a broader effort to bump golangci-lint across LaunchDarkly Go repositories, matching ld-relay#586.

Review & Testing Checklist for Human

• Verify that nolint:staticcheck is the correct linter name for suppressing the ST1005 (capitalized error string) rule in golangci-lint v2 — stylecheck no longer exists as a standalone linter
• Confirm CI lint job passes cleanly with the new v2.11.1 version (this repo has no .golangci.yml, so it relies entirely on default linter settings which changed between v1 and v2)
• Check that suppressing errcheck on defer store.Close() in the test is acceptable rather than handling the error explicitly

Notes

Link to Devin session: https://app.devin.ai/sessions/45faa2d1c22c41c6beab7ce8e891bc96
Requested by: @keelerm84

---

Note

Low Risk
Low risk: build tooling change plus comment-level lint suppressions; no runtime behavior is altered beyond ignoring a Close() error in a test defer.

Overview
Bumps golangci-lint to v2.11.1 in the Makefile.

Fixes newly surfaced lint failures by updating the Consul transaction error suppression to //nolint:staticcheck in consul_impl.go and adding //nolint:errcheck for defer store.Close() in consul_test.go.

^{Written by Cursor Bugbot for commit bc0d188. This will update automatically on new commits. Configure here.}

[devin-ai-integration]

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