feat(host-agent): Phase 2 — Dune docker-compose adapter via Supervisor trait

Introduce a Supervisor trait (async-trait) so the agent manages games with
different models behind one wire contract. ProcessSupervisor (spawned process:
rust/conan/soulmask) and the new DockerComposeSupervisor (dune) both impl it;
Agent.supervisors is now HashMap<String, Arc<dyn Supervisor>> and instancecmd
dispatch is game-agnostic — start/stop/restart/status identical across games,
selected by a per-game factory in main. InstanceState moved to the shared
supervisor module.

DockerComposeSupervisor drives docker-compose up-d / stop / restart against
the instance's compose project, with -f/-p/single-service support and a
configurable compose binary. New [instance.docker_compose] config block.
First cut = lifecycle + cached state; container crash-detection + restart
adoption deferred to Phase 3b (reconcilable with a compose ps probe).

Trait choice (dyn over enum) per Commander: scales to future planes (kubectl,
AMP/podman, SSH) as new struct+impl, no central match.

56 tests green (6 new docker-compose mock-binary tests + 5 refactored process
tests), zero warnings. Live verification pending a real Dune stack.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

corrosion-host-agent/tests/supervisor.rs

@@ -8,7 +8,8 @@ use std::path::PathBuf;
 use std::time::Duration;
 
 use corrosion_host_agent::config::InstanceConfig;
-use corrosion_host_agent::process::{InstanceState, ProcessSupervisor};
+use corrosion_host_agent::process::ProcessSupervisor;
+use corrosion_host_agent::supervisor::{InstanceState, Supervisor};
 
 fn managed_instance(executable: &str, args: &[&str]) -> InstanceConfig {
     InstanceConfig {
@@ -21,6 +22,7 @@ fn managed_instance(executable: &str, args: &[&str]) -> InstanceConfig {
         working_dir: None,
         rcon: None,
         steamcmd: None,
+        docker_compose: None,
     }
 }
 
@@ -47,15 +49,15 @@ async fn start_status_stop_lifecycle() {
     let sup = ProcessSupervisor::new(&managed_instance("/bin/sleep", &["300"]));
     assert_eq!(sup.state(), InstanceState::Stopped);
 
-    sup.start().await.expect("start should succeed");
+    sup.clone().start().await.expect("start should succeed");
     assert_eq!(sup.state(), InstanceState::Running);
     tokio::time::sleep(Duration::from_millis(1100)).await;
     assert!(sup.uptime_seconds().await >= 1, "uptime should advance");
 
     // Double-start must be rejected while running.
-    assert!(sup.start().await.is_err(), "double start must fail");
+    assert!(sup.clone().start().await.is_err(), "double start must fail");
 
-    sup.stop().await.expect("stop should succeed");
+    sup.clone().stop().await.expect("stop should succeed");
     let state = wait_for_state(&sup, |s| matches!(s, InstanceState::Stopped), Duration::from_secs(5)).await;
     assert_eq!(state, InstanceState::Stopped);
     assert_eq!(sup.uptime_seconds().await, 0);
@@ -64,7 +66,7 @@ async fn start_status_stop_lifecycle() {
 #[tokio::test]
 async fn unexpected_exit_is_crashed_with_code() {
     let sup = ProcessSupervisor::new(&managed_instance("/bin/sh", &["-c", "sleep 0.2; exit 7"]));
-    sup.start().await.expect("start should succeed");
+    sup.clone().start().await.expect("start should succeed");
 
     let state = wait_for_state(
         &sup,
@@ -78,16 +80,16 @@ async fn unexpected_exit_is_crashed_with_code() {
 #[tokio::test]
 async fn restart_from_crashed_recovers() {
     let sup = ProcessSupervisor::new(&managed_instance("/bin/sh", &["-c", "exit 1"]));
-    sup.start().await.expect("start should succeed");
+    sup.clone().start().await.expect("start should succeed");
     wait_for_state(&sup, |s| matches!(s, InstanceState::Crashed { .. }), Duration::from_secs(5)).await;
 
     // Restart from crashed must work (panel "Restart" after a crash).
     // Use a long-lived command this time by replacing the supervisor — the
     // command is fixed per supervisor, so emulate via a fresh one.
     let sup2 = ProcessSupervisor::new(&managed_instance("/bin/sleep", &["300"]));
-    sup2.restart().await.expect("restart from stopped should start");
+    sup2.clone().restart().await.expect("restart from stopped should start");
     assert_eq!(sup2.state(), InstanceState::Running);
-    sup2.stop().await.expect("cleanup stop");
+    sup2.clone().stop().await.expect("cleanup stop");
 }
 
 #[tokio::test]
@@ -96,14 +98,14 @@ async fn unmanaged_instance_rejects_process_commands() {
     cfg.executable = None;
     let sup = ProcessSupervisor::new(&cfg);
     assert_eq!(sup.state(), InstanceState::Unmanaged);
-    assert!(sup.start().await.is_err(), "unmanaged start must fail");
-    assert!(sup.stop().await.is_err(), "unmanaged stop must fail");
+    assert!(sup.clone().start().await.is_err(), "unmanaged start must fail");
+    assert!(sup.clone().stop().await.is_err(), "unmanaged stop must fail");
 }
 
 #[tokio::test]
 async fn missing_executable_fails_cleanly() {
     let sup = ProcessSupervisor::new(&managed_instance("/nonexistent/bin/gameserver", &[]));
-    let err = sup.start().await.expect_err("must fail");
+    let err = sup.clone().start().await.expect_err("must fail");
     assert!(err.to_string().contains("not found"), "error should say not found: {err}");
     assert_eq!(sup.state(), InstanceState::Stopped, "failed start must not leave Starting state");
 }