docs: port kafka connect sink type/schema mapping updates

[mintlify]

Summary

Ports upstream PR ClickHouse/clickhouse-docs#6427 ("Kafka Update Type and Schema mapping docs") into the Mintlify site.

Changes

• integrations/connectors/data-ingestion/kafka/kafka-clickhouse-connect-sink.mdx
  • Promoted the Avro / Protobuf / JSON / String schema sections from #####/###### to ###/#### and removed the now-redundant "Using with different data formats" wrapper heading (slugs preserved).
  • Compacted the Avro type-mapping table (removed column padding) and fixed analagously → analogously.
  • Expanded the Protobuf type-mapping table with a new ClickHouse Type column, refreshed message/oneof mappings (Tuple / JSON, Tuple / Variant), and added rows for google.protobuf.Duration, google.protobuf.Any, and google.protobuf.Empty.

Context

• Trigger commit: f8f2881 (merge of upstream PR #6427) on clickhouse/clickhouse-docs.
• Slug of the file is preserved so it continues to map 1:1 with the Docusaurus source.
• The upstream PR also adds Protobuf to styles/ClickHouse/Headings.yml (Vale linter config). That file has no Mintlify counterpart and was intentionally skipped.
• i18n translation directories (es/, ja/, ko/, pt-BR/, ru/, zh/) were intentionally skipped per the porting instructions.
• One link was left as-is rather than matched to upstream: the link to allow_experimental_nullable_tuple_type already points at the Mintlify-style path /reference/settings/session-settings#..., while upstream uses /operations/settings/settings#.... Flagging as a minor ambiguity — happy to align if there's a preferred convention.

[mintlify]

Preview deployment for your docs. Learn more about Mintlify Previews.

Project	Status	Preview	Updated (UTC)
ClickHouse-docs	🟢 Ready	View Preview	Jun 23, 2026, 2:46 PM