golangci-lint JSON trailer is parsed as a clean run #15

Summary

parseGolangciLintJson in src/harness/check-engine/output-parsers-extra.ts passes golangci-lint stdout straight to JSON.parse. golangci-lint v2, invoked with --output.json.path stdout, writes the JSON report and then a text trailer on the same stream, for example:

{ "Issues": [ ... ] }
1 issues:
* errcheck: 1

JSON.parse rejects that trailer (Unexpected non-whitespace character after JSON). The parser's catch returns []. interlinked check --only golangci-lint then reports count: 0 and exits 0, which is a false clean when the report contains issues.

This is separate from the removed --out-format flag (#11) and from non-success exit codes (#13). Those can be correct and this parse still drops the issues, because exit 1 (IssuesFound) is the path that parses stdout.

Expected

Read the first JSON object and ignore the text trailer. An issue list in that object is returned as findings. Output that is not JSON still returns no findings.