Add secure field to ClickHouse connection config

[meteoFurletov]

Summary

• Add secure: bool = False field to ClickhouseConnectionConfig for explicitly enabling HTTPS/TLS
• Add "secure" to _connection_kwargs_keys so it gets passed through to clickhouse_connect.dbapi.connect()

Problem

There is currently no way to explicitly enable HTTPS/TLS on a ClickHouse connection via SQLMesh config. Users must rely on port-based auto-detection (port 8443), which doesn't always work — especially when SQLMesh provides its own pool manager via connection_pool_options.

The clickhouse-connect library's dbapi.connect() already accepts a secure parameter (bool) that controls HTTPS/TLS, but ClickhouseConnectionConfig doesn't expose it.

Fix

Expose the secure parameter that clickhouse-connect already supports:

1. Added secure: bool = False field after tls_mode in the HTTPS/TLS settings section
2. Added "secure" to the _connection_kwargs_keys set so it's passed to connect()

Backwards compatibility

Fully backwards-compatible — defaults to False, matching the current behavior.

Test plan

• Verified the field is added and passed through via _connection_kwargs_keys
• Users can set secure: true in their config.yaml to enable HTTPS/TLS

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