feat(pull): add get_comments method to pull_request_read

List regular PR discussion comments via the issue comments endpoint,
since Gitea pull requests are issues internally. Reuses the issue
package's slim comment shape with attachment inlining.

Co-Authored-By: Codet <codet@commitgo.dev> (GPT-5-Codex)

operation/pull/slim.go

@@ -164,3 +164,17 @@ func slimReviewComments(comments []*gitea_sdk.PullReviewComment) []map[string]an
 	}
 	return out
 }
+
+func slimComment(c *gitea_sdk.Comment) map[string]any {
+	if c == nil {
+		return nil
+	}
+	return map[string]any{
+		"id":         c.ID,
+		"body":       c.Body,
+		"user":       slim.UserLogin(c.Poster),
+		"html_url":   c.HTMLURL,
+		"created_at": c.Created,
+		"updated_at": c.Updated,
+	}
+}