ClickHouse connector

Connects to ClickHouse over the shared SQL DB-API base (lazy connect, JSON-safe value coercion, reconnect-and-retry) via clickhouse-connect, ClickHouse's official HTTP client. Works with self-hosted ClickHouse and ClickHouse Cloud.

# sources.yaml
events:
  type: clickhouse
  host: ${CH_HOST}
  port: 8443
  database: analytics
  user: ${CH_USER}
  password: ${CH_PASSWORD}
  secure: true          # TLS — required by ClickHouse Cloud

Key	Purpose
`host` / `port`	Server address. Port is optional — the driver defaults to `8123` (`8443` when `secure`).
`database`	Database name (`db` also accepted).
`user` / `password`	Credentials (`username` also accepted).
`secure`	Connect over TLS.
`dsn` / `url`	…or a single `clickhouse://user:pass@host:port/db` URL instead of the above.
`connect_args`	Extra kwargs passed to the driver.

Install: uv add 'dashdown-md[clickhouse]' (or pip install 'dashdown-md[clickhouse]'). Secrets support ${ENV_VAR} expansion — keep them out of the YAML.