test: cover hybridChunkSize forwarding in Node bindings

Problem

The regenerated Node bindings (convert-options.generated.ts) forward --hybrid-chunk-size in buildArgs/buildConvertOptions, but no test covers those branches, despite an existing comprehensive test file for sibling options (node/opendataloader-pdf/test/convert-options.test.ts).

Suggested fix

Extend convert-options.test.ts: add hybridChunkSize to the 'handle all options together' buildArgs test and the buildConvertOptions pass-through test.

Severity: P3 | Confidence: 75 | Reviewer(s): testing