controller: publish getconfig metrics to clickhouse

[nikw9944]

Summary of Changes

• Add ClickHouse integration to the controller to record successful GetConfig gRPC calls for device health tracking as per rfc12
• New ClickhouseWriter batches events every 10 seconds and writes to a controller_grpc_getconfig_success table partitioned by month
• ClickHouse is opt-in, configured via environment variables: CLICKHOUSE_ADDR, CLICKHOUSE_DB, CLICKHOUSE_USER, CLICKHOUSE_PASS, CLICKHOUSE_TLS_DISABLED
• CLICKHOUSE_TLS_DISABLED is only intended for use in e2e tests and testing with a local clickhouse instance
• Logs on startup whether ClickHouse is enabled or disabled, including connection details (addr, db, user)
• Table is auto-created with CREATE TABLE IF NOT EXISTS so it's safe across restarts

Testing Verification

• Tested by hand in devnet