* fix(cli): write embed generate output in the format embed index reads
* Address review: structured results get their own --output writer
deduplicate --output and ontology align --output were routed through
_write_embeddings_output, a helper for numeric matrices: it rejects the
dict/list shapes these commands produce and the .csv extension deduplicate
documents. New _write_result_output serializes structured results — JSON,
JSON-lines for lists, CSV for rows — and both commands use it. embed
generate keeps the embeddings writer, whose strictness is what #994 fixed.
On the pyarrow gap: the parquet writer already fails with an actionable
message (install pyarrow or use .json). Silently writing JSON bytes to a
.parquet path would recreate #994's magic-bytes failure, so the error stays
an error and the default suggestion stays .json.
* fix(cli): improve structured output serialization
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Co-authored-by: Sameer6305 <sskadam6305@gmail.com>
