All services migrated to Go 1.25+ due to performance improvements from Go 1.25.
This aligns with GitLab's Go version policy of supporting 3 latest minor versions.

golangci-lint 1.64 was built with Go 1.24 and cannot lint code targeting Go 1.25.
Upgrade to 1.66 which supports Go 1.25.

Updated both .golangci.yaml files for golangci-lint v2.11.4:
- Changed version to 2 (required for v2)
- Removed unsupported linters (gofumpt formatter, tenv, stylecheck)
- Simplified depguard config for v2 format
- Removed deprecated output section properties
- Config validated and linting runs successfully locally

Fixed all 33 errcheck and staticcheck errors in the root module:
- Added proper error handling for unchecked function returns
- Fixed defer statements to check for close errors
- Replaced empty struct context key with proper type definition in metrics/handler_test.go

All linting now passes in the root module.

Addresses all remaining errcheck and staticcheck errors in the v2 module
after upgrading to golangci-lint 2.11.4 and Go 1.25.0. Includes:
- Wrapping unchecked Shutdown/Close operations with error ignores
- Adding proper error handling for fmt.Print operations
- Removing unnecessary type annotations per staticcheck recommendations
- Fixing unchecked JSON unmarshaling and function returns in tests

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Replace non-idiomatic error handling patterns with Go conventions:

- Change defer cleanup from `defer func() { _ = obj.Close() }()` to
  idiomatic `defer obj.Close()`. Errors from cleanup are implicitly
  ignored per Go idiom — no wrapper needed.
- Remove explicit `_, _ =` assignments for fmt.Fprint to
  http.ResponseWriter. Write errors are conventionally ignored
  without assignment.
- Add proper error checking in example code where operations can fail
  (http.ListenAndServe, server.Serve).

This addresses feedback that the previous linter fixes were assigning
errors to `_` indiscriminately instead of following best practices.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Document that errors from write operations to http.ResponseWriter and
cleanup operations (Close, Shutdown) are deliberately ignored in test
and example code using the standard //nolint:errcheck directive.

This satisfies the errcheck linter while making intent explicit: we are
aware these operations return errors, but they are acceptable to ignore
in test/example contexts.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Add nolint directives to fmt.Fprintf/Fprintln calls to os.Stdout/Stderr
and other fmt.Fprint calls that were missed in the initial pass.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

chore: deprecate Go 1.24 support

See merge request !440

Merged-by: Matias Alvarez <malvarez@gitlab.com>
Approved-by: Matias Alvarez <malvarez@gitlab.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>
Reviewed-by: Matias Alvarez <malvarez@gitlab.com>
Co-authored-by: e_forbes <eforbes@gitlab.com>