Comment creation fails on GitLab <= 17.7

Start in cmd/app/comment_helpers.go at buildCommentPosition and inspect how LineRangeOptions is assembled for review comments and draft notes. Compare the serialized position with GitLab 17.7's accepted schema, then verify that comment creation no longer returns the 400 validation error.

Posting a review comment / draft note fails with a 400 Bad Request from the GitLab API:

{"message": {"position": ["must be a valid json schema"]}}

Environment

• gitlab.nvim commit: 80edb27 / f05aee3 (latest)
• GitLab version: 17.7.1 (self-hosted)

Root Cause
In commit 80edb27 (fix: get correct location data for comments efficiently), OldLine and NewLine were added to opt.LineRange.Start and opt.LineRange.End in cmd/app/comment_helpers.go:

opt.LineRange = &gitlab.LineRangeOptions{
    Start: &gitlab.LinePositionOptions{
        Type:     &positionData.LineRange.Start.Type,
        LineCode: &startFilenameSha,
        OldLine:  &startOldLine,
        NewLine:  &startNewLine,
    },
    ...
}

This causes the Go backend to serialize:

"line_range": {
  "start": {
    "line_code": "...",
    "type": "new",
    "old_line": 0,
    "new_line": 36
  }
}

GitLab's REST API validates position against app/validators/json_schemas/position.json. In GitLab $\le$ 17.7, line_range.start and line_range.end enforce "additionalProperties": false and only permit "line_code" and "type". As a result, including old_line or new_line causes schema validation to fail.

Fix
In cmd/app/comment_helpers.go, keep OldLine and NewLine nil / omitted from LinePositionOptions:

--- a/cmd/app/comment_helpers.go
+++ b/cmd/app/comment_helpers.go
@@ -83,14 +83,10 @@ func buildCommentPosition(commentWithPositionData RequestWithPosition) *gitlab.P
 	opt.LineRange = &gitlab.LineRangeOptions{
 		Start: &gitlab.LinePositionOptions{
 			Type:     &positionData.LineRange.Start.Type,
 			LineCode: &startFilenameSha,
-			OldLine:  &startOldLine,
-			NewLine:  &startNewLine,
 		},
 		End: &gitlab.LinePositionOptions{
 			Type:     &positionData.LineRange.End.Type,
 			LineCode: &endFilenameSha,
-			OldLine:  &endOldLine,
-			NewLine:  &endNewLine,
 		},
 	}