NDJSON streaming for large results

[rodaddy]

Stream large result sets as newline-delimited JSON.

• --stream flag enables NDJSON output
• Each line is a complete JSON object
• Prevents OOM on very large responses

Requirement: ADV-04

[rodaddy]

NDJSON format implemented in src/format/ndjson.ts and accessible via --format ndjson. Outputs one JSON object per line for array results. True streaming (write-as-received to prevent OOM on very large results) is a future optimization — current implementation covers the format requirement.