fix(runtime): stop/restart d'agent visible robuste — kill réel, état stopped, relance froide (#196, QA verte)

Solidifie le cycle stop/restart d'un agent visible en cellule:

- terminal/registry: kill effectif de la TUI native et de la CLI custom, arrêt idempotent du live runtime (PTY + structuré), distinction nette « agent stoppé » vs « pas de session ».

- workstate + lifecycle: projection d'un état runtime explicite « stopped » (AgentRuntimeState: running/stopping/stopped/failedStart), réconcilié avec le live state; traitement des courses « agent not found ».

- relance froide via freshStart: repart de zéro sans réattacher une session morte et recharge la configuration courante de l'agent (y compris changement de modèle).

- contrat projeté côté adapters frontend (ports/domain/normalization/mock) pour la consommation UI future (#197/#198), sans surface UI ici.

Tests QA verts: workstate_actions, orchestrator_service stop_agent, agent_lifecycle (reopen/fresh_start), workstate stopped runtime state, vitest adapter stop_live_agent.

crates/application/tests/workstate_actions.rs

@@ -11,8 +11,8 @@ use std::sync::{Arc, Mutex};
 use async_trait::async_trait;
 
 use application::{
-    AttachLiveAgent, AttachLiveAgentInput, CloseTerminal, LiveSessionKind, LiveSessions,
-    StopAgentExecutionCascade, StopLiveAgent, StopLiveAgentInput, StructuredSessions,
+    AttachLiveAgent, AttachLiveAgentInput, CloseTerminal, LiveRuntimeState, LiveSessionKind,
+    LiveSessions, StopAgentExecutionCascade, StopLiveAgent, StopLiveAgentInput, StructuredSessions,
     TerminalSessions,
 };
 use domain::ports::{
@@ -329,7 +329,9 @@ async fn stop_pty_kills_and_removes_session() {
 
     assert_eq!(out.agent_id, a);
     assert_eq!(out.session_id, sid(1));
+    assert_eq!(out.node_id, nid(100));
     assert_eq!(out.kind, LiveSessionKind::Pty);
+    assert_eq!(out.runtime_state, LiveRuntimeState::Stopped);
     // Delegated to the close primitive: process killed and registry emptied.
     assert_eq!(f.pty_port.kills(), vec![sid(1)]);
     assert!(f.pty.is_empty(), "live session removed from the registry");
@@ -353,6 +355,7 @@ async fn stop_structured_shuts_down_and_removes_session() {
 
     assert_eq!(out.session_id, sid(2));
     assert_eq!(out.kind, LiveSessionKind::Structured);
+    assert_eq!(out.runtime_state, LiveRuntimeState::Stopped);
     assert!(flag.load(Ordering::SeqCst), "session.shutdown() was called");
     assert!(f.structured.is_empty(), "live session removed");
     assert_eq!(
@@ -388,6 +391,34 @@ async fn stop_structured_runs_execution_cascade_best_effort() {
     assert!(f.structured.is_empty(), "live session removed");
 }
 
+#[tokio::test]
+async fn stop_pty_is_idempotent_after_success() {
+    let f = fixture();
+    let a = aid(10);
+    insert_pty(&f.pty, sid(1), a, nid(100));
+
+    let first = f
+        .stop
+        .execute(StopLiveAgentInput {
+            project: project(),
+            agent_id: a,
+        })
+        .await
+        .unwrap();
+    let second = f
+        .stop
+        .execute(StopLiveAgentInput {
+            project: project(),
+            agent_id: a,
+        })
+        .await
+        .unwrap();
+
+    assert_eq!(first, second);
+    assert_eq!(second.runtime_state, LiveRuntimeState::Stopped);
+    assert_eq!(f.pty_port.kills(), vec![sid(1)], "kill is not repeated");
+}
+
 #[tokio::test]
 async fn stop_unknown_agent_is_not_found() {
     let f = fixture();