Native TCP: CompressionMethod::ZSTD is not honored for server -> client blocks (network_compression_method never sent)

## Description

When a client is configured with `ClientOptions().SetCompressionMethod(CompressionMethod::ZSTD)`, only the **client → server** direction actually uses ZSTD. The **server → client** direction still uses the server's default codec (LZ4).

The reason is that the native TCP query packet only carries a boolean "compression enabled" flag; the selected codec is never propagated to the server:

* `clickhouse/client.cpp:349-351` — `compression_` is set to `CompressionState::Enable` for any method other than `None`; the specific method is discarded.
* `clickhouse/client.cpp:1087` — `WireFormat::WriteUInt64(*output_, compression_);` writes only that enable flag.
* `clickhouse/client.cpp:447` — `CompressedOutput` correctly uses `options_.compression_method` for the outgoing (client → server) data blocks.

To make the server compress its responses with ZSTD, the client must send the `network_compression_method` (and, for a configured level, `network_zstd_compression_level`) setting in the per-query settings section of the query packet (`clickhouse/client.cpp:1067-1080`). It never does.

The read path is not broken — `CompressedInput::Decompress` (`clickhouse/base/compressed.cpp:105-131`) accepts both LZ4 and ZSTD method bytes — so nothing fails; the selected codec is just silently not honored in one direction.

Additionally, there is no option to configure a ZSTD compression level at all: `ClientOptions` (`clickhouse/client.h:107`) only exposes `compression_method`.

This is the C++ equivalent of ClickHouse/clickhouse-go#1993.

## ClickHouse server version

`26.7.5.10` (verified against a running server over the native protocol on port 9000).

## Reproduction

The server-side effective value of `network_compression_method` for the query is what determines how the server compresses the result blocks it sends back, so it can be observed directly from the client:

```cpp
#include
#include

using namespace clickhouse;

int main() {
Client client(ClientOptions()
.SetHost("localhost")
.SetPort(9000)
.SetCompressionMethod(CompressionMethod::ZSTD));

client.Select(
"SELECT name, value FROM system.settings WHERE name IN "
"('network_compression_method', 'network_zstd_compression_level')",
[](const Block& block) {
for (size_t i = 0; i < block.GetRowCount(); ++i) {
std::cout << (*block[0]->As())[i] << " = "
<< (*block[1]->As())[i] << std::endl;
}
});
return 0;
}
```

Expected output (codec honored in both directions):

```
network_compression_method = ZSTD
network_zstd_compression_level =
```

Actual output:

```
network_compression_method = LZ4
network_zstd_compression_level = 1
```

i.e. the server compresses everything it sends back to this client with LZ4, even though ZSTD was requested.

## Suggested fix

In `Client::Impl::SendQuery` (`clickhouse/client.cpp`, per-query settings block around lines 1067-1080), when `options_.compression_method != CompressionMethod::None` and the setting is not already present in `query.GetQuerySettings()`, send:

* `network_compression_method` = `"ZSTD"` / `"LZ4"` matching `options_.compression_method`
* `network_zstd_compression_level` = the configured level, if a new `ClientOptions` field for it is added (e.g. `SetCompressionLevel`), when the method is ZSTD

## Link

Original report against the Go client: https://github.com/ClickHouse/clickhouse-go/issues/1993