feat(host-agent): Phase 1a process supervision — instance start/stop/restart/status + push state events

Per-instance ProcessSupervisor: tokio child spawn with proper arg list
(fixes Go's naive space-splitting), graceful SIGTERM with 30s budget
then force kill, monitor task classifying ordered-stop vs crash (exit
code captured), watch-channel state observable everywhere. Instance cmd
channel live on corrosion.{license}.{instance}.cmd (start/stop/restart/
status) with state events pushed on {instance}.status (keep-latest
semantics, documented). Heartbeats now carry live process state +
uptime per instance. Crate restructured lib+bin for integration tests.

Verified: 5 integration tests with real OS processes (lifecycle, crash
exit-code, restart recovery, unmanaged rejection, clean spawn failure)
+ live-NATS contract test (request-reply roundtrips, double-start
rejection, push events, heartbeat state) — all green.

Known limitation (documented): no PID adoption yet — agent restart
orphans a running game process to 'stopped' until panel restart.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

corrosion-host-agent/src/telemetry.rs

@@ -65,9 +65,10 @@ pub struct InstanceInfo {
     pub game: String,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub label: Option<String>,
-    /// Phase 0 states: `configured` (root exists) or `missing_root`.
-    /// Phase 1 adds live process states (running/stopped/crashed).
+    /// Process-managed: running/stopped/starting/stopping/crashed.
+    /// Unmanaged (no executable configured): configured/missing_root.
     pub state: String,
+    pub uptime_seconds: u64,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub root_disk_free_mb: Option<u64>,
 }
@@ -125,21 +126,30 @@ pub async fn collect(agent: &Agent, sys: &mut System) -> HeartbeatPayload {
         })
         .collect();
 
-    let instances = agent
-        .cfg
-        .instances
-        .iter()
-        .map(|inst| {
-            let exists = inst.root.exists();
-            InstanceInfo {
-                id: inst.id.clone(),
-                game: inst.game.clone(),
-                label: inst.label.clone(),
-                state: if exists { "configured" } else { "missing_root" }.to_string(),
-                root_disk_free_mb: disk_free_for_path(&disks, &inst.root),
+    let mut instances = Vec::with_capacity(agent.cfg.instances.len());
+    for inst in &agent.cfg.instances {
+        let (state, uptime_seconds) = match agent.supervisors.get(&inst.id) {
+            Some(sup) if !matches!(sup.state(), crate::process::InstanceState::Unmanaged) => {
+                (sup.state().as_label().to_string(), sup.uptime_seconds().await)
             }
-        })
-        .collect();
+            _ => {
+                let exists = inst.root.exists();
+                (
+                    if exists { "configured" } else { "missing_root" }.to_string(),
+                    0,
+                )
+            }
+        };
+        instances.push(InstanceInfo {
+            id: inst.id.clone(),
+            game: inst.game.clone(),
+            label: inst.label.clone(),
+            state,
+            uptime_seconds,
+            root_disk_free_mb: disk_free_for_path(&disks, &inst.root),
+        });
+    }
+    let instances = instances;
 
     HeartbeatPayload {
         schema: 2,