Export AddImportFix and improve GCI-aware import insertion

[Copilot]

addImportFix was package-private, forcing every new checker (negated-assert, graceful-teardown, …) to either duplicate it or add export_test.go workarounds. Import insertion also blindly appended non-stdlib packages before ), which breaks GCI group ordering when a file has blank-line-separated import groups.

Changes

• helpers_import.go — addImportFix → AddImportFix (exported); importInsertEdit now scans non-stdlib specs in file order and inserts before the first spec whose path is lexicographically greater, instead of appending at the end:

// Before: assert always appended last — ends up after require (and after local groups)
import (
    "testing"

    "github.com/stretchr/testify/require"
    "github.com/stretchr/testify/assert" // ← wrong position
)

// After: assert inserted before require (a < r); blank-line GCI groups preserved
import (
    "testing"

    "github.com/stretchr/testify/assert" // ← correct
    "github.com/stretchr/testify/require"
)

• helpers_http.go — httpNetPkgName updated to call AddImportFix.
• helpers_import_test.go — added unit tests for AddImportFix: already-imported (no-op edit), GCI ordering, GCI group boundary preservation across blank lines, and blank-import (ok=false).

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[mmorel-35]

@copilot ,
Don't forget to pass golangci-lint v2.4.0 and tests

[Copilot]

@copilot ,
Don't forget to pass golangci-lint v2.4.0 and tests

Fixed in fb0557a. The helpers_import_test.go import block was missing tab indentation (a heredoc artifact from the initial write), which caused the gci formatter to report an error. Applied golangci-lint run --fix to auto-correct the formatting — golangci-lint run ./... now reports 0 issues and all tests pass.