fix: mount JAR volume on provisioned server containers

The server needs a shared Docker volume at /data/jars to store
uploaded JARs that deployed app containers can access. Without this
mount, deployed containers fail with "Unable to access jarfile".

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main/java/net/siegeln/cameleer/saas/provisioning/DockerTenantProvisioner.java

@@ -163,7 +163,10 @@ public class DockerTenantProvisioner implements TenantProvisioner {
         HostConfig hostConfig = HostConfig.newHostConfig()
             .withRestartPolicy(RestartPolicy.unlessStoppedRestart())
             .withNetworkMode(tenantNetwork)
-            .withBinds(new Bind("/var/run/docker.sock", new Volume("/var/run/docker.sock")))
+            .withBinds(
+                new Bind("/var/run/docker.sock", new Volume("/var/run/docker.sock")),
+                new Bind("cameleer-jars-" + slug, new Volume("/data/jars"))
+            )
             .withGroupAdd(List.of("0"));
 
         CreateContainerResponse resp = docker.createContainerCmd(props.serverImage())