SSH writePacket can block indefinitely in 2.11.0 – proposal to add configurable write timeout

### Version

Apache MINA SSHD 2.11.0 Client side, NETCONF over SSH

### Bug description

Threads block indefinitely in DefaultSshFuture.await() during writePacket()
when peer stops reading or TCP buffer fills.
Observed in production: threads stuck for hours.

```
"CentralPool-alarm-rule-translation-pool-565890" #565890 prio=5 os_prio=0 cpu=2241.46ms elapsed=23171.52s tid=0x00007f45583eecf0 nid=0x254b33 in Object.wait() [0x00007f36c7efd000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(java.base@17.0.8/Native Method)
- waiting on
at org.apache.sshd.common.future.DefaultSshFuture.await0(DefaultSshFuture.java:80)
- locked <0x000000048b3c6430> (a java.lang.Object)
at org.apache.sshd.common.future.AbstractSshFuture.await(AbstractSshFuture.java:58)
at org.apache.sshd.common.future.WaitableFuture.await(WaitableFuture.java:50)
at org.apache.sshd.common.session.helpers.KeyExchangeMessageHandler.writeOrEnqueue(KeyExchangeMessageHandler.java:355)
at org.apache.sshd.common.session.helpers.KeyExchangeMessageHandler.writePacket(KeyExchangeMessageHandler.java:248)
at org.apache.sshd.common.session.helpers.AbstractSession.writePacket(AbstractSession.java:1027)
at org.apache.sshd.common.channel.AbstractChannel.writePacket(AbstractChannel.java:812)
at org.apache.sshd.common.channel.throttle.DefaultChannelStreamWriter.writeData(DefaultChannelStreamWriter.java:46)
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.writePacket(ChannelAsyncOutputStream.java:347)
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.doWriteIfPossible(ChannelAsyncOutputStream.java:224)
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.writeBuffer(ChannelAsyncOutputStream.java:118)
at org.broadband_forum.obbaa.netconf.client.ssh.SshNetconfClientSession.sendRpcMessage(SshNetconfClientSession.java:87)
- locked <0x000000044d56bcd0> (a org.broadband_forum.obbaa.netconf.client.ssh.SshNetconfClientSession)
at org.broadband_forum.obbaa.netconf.client.ssh.SshNetconfClientSession.sendRpcMessage(SshNetconfClientSession.java:70)
- locked <0x000000044d56bcd0> (a org.broadband_forum.obbaa.netconf.client.ssh.SshNetconfClientSession)
at org.broadband_forum.obbaa.netconf.api.client.AbstractNetconfClientSession.sendRpcAndGetFuture(AbstractNetconfClientSession.java:145)
at org.broadband_forum.obbaa.netconf.api.client.AbstractNetconfClientSession.sendRpc(AbstractNetconfClientSession.java:138)
at org.broadband_forum.obbaa.netconf.api.client.AbstractNetconfClientSession.get(AbstractNetconfClientSession.java:122)
at com.alcatel.pma.core.configmgmt.DeviceNetconfSessionImpl.get(DeviceNetconfSessionImpl.java:237)
```

```
"CentralPool-nbi-request-pool-572076" #572076 prio=5 os_prio=0 cpu=201.60ms elapsed=16925.79s tid=0x00007f455843fdc0 nid=0x257fe8 in Object.wait() [0x00007f36c6bfd000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(java.base@17.0.8/Native Method)
- waiting on
at org.apache.sshd.common.future.DefaultSshFuture.await0(DefaultSshFuture.java:80)
- locked <0x0000000545cb0828> (a java.lang.Object)
at org.apache.sshd.common.future.AbstractSshFuture.await(AbstractSshFuture.java:58)
at org.apache.sshd.common.future.WaitableFuture.await(WaitableFuture.java:50)
at org.apache.sshd.common.session.helpers.KeyExchangeMessageHandler.writeOrEnqueue(KeyExchangeMessageHandler.java:355)
at org.apache.sshd.common.session.helpers.KeyExchangeMessageHandler.writePacket(KeyExchangeMessageHandler.java:248)
at org.apache.sshd.common.session.helpers.AbstractSession.writePacket(AbstractSession.java:1027)
at org.apache.sshd.common.channel.AbstractChannel.writePacket(AbstractChannel.java:812)
at org.apache.sshd.common.channel.throttle.DefaultChannelStreamWriter.writeData(DefaultChannelStreamWriter.java:46)
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.writePacket(ChannelAsyncOutputStream.java:347)
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.doWriteIfPossible(ChannelAsyncOutputStream.java:224)
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.writeBuffer(ChannelAsyncOutputStream.java:118)
at org.broadband_forum.obbaa.netconf.client.ssh.SshNetconfClientSession.sendRpcMessage(SshNetconfClientSession.java:87)
- locked <0x0000000545cb0b40> (a org.broadband_forum.obbaa.netconf.client.ssh.SshNetconfClientSession)
```

### Actual behavior

SSH writePacket can block indefinitely in 2.11.0.

### Expected behavior

Write operations should respect a configurable timeout and fail fast.

### Relevant log output

```Shell

```

### Other information

We did following code change to add configurable timeout:

### AbstractSession.java
```
private final long ssh_timeout_seconds = CoreModuleProperties.SSH_TIMEOUT_SECONDS.getRequired(this);
```

```
@Override
public IoWriteFuture writePacket(Buffer buffer) throws IOException {
log.info("Triggers KEX Handler write packet with timeout {}", ssh_timeout_seconds);
return kexHandler.writePacket(buffer, ssh_timeout_seconds, null);
}
```

### CoreModuleProperties.java
```
public static final Property SSH_TIMEOUT_SECONDS
= Property.long_("ssh-timeout-seconds", 300L);
```

Before raising a PR, I’d like feedback whether this approach and location
for timeout handling is acceptable.

Start by tracing AbstractSession.writePacket through KeyExchangeMessageHandler.writePacket and inspect the existing await path shown in the stack trace. Review CoreModuleProperties.java and the proposed ssh-timeout-seconds property; done means write operations use a configurable timeout and fail instead of blocking indefinitely.

Written by the indexing model from the issue text.