feat(workstate): UI des actions contrôlées (Lot D frontend)

Câble les actions contrôlées dans ProjectWorkStatePanel : port et adaptateur
agent étendus aux nouvelles commandes, adaptateur mock aligné.

Tests verts : workstate + projects (25), agent (8), singletonAgent +
agentAlreadyRunning (9), tsc --noEmit OK.

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

frontend/src/adapters/mock/index.ts

@@ -61,6 +61,7 @@ import type {
   ReattachResult,
   RemoteGateway,
   SkillGateway,
+  StoppedLiveAgent,
   SystemGateway,
   TemplateGateway,
   TerminalGateway,
@@ -215,7 +216,8 @@ export class MockAgentGateway implements AgentGateway {
       .map(([agentId, nodeId]) => ({
         agentId,
         nodeId,
-        sessionId: this.liveSessionByAgent.get(agentId),
+        sessionId: this.liveSessionByAgent.get(agentId)!,
+        kind: "pty" as const,
       }));
   }
 
@@ -256,7 +258,32 @@ export class MockAgentGateway implements AgentGateway {
       throw err;
     }
     this.liveByAgent.set(agentId, nodeId);
-    return { agentId, nodeId, sessionId };
+    return { agentId, nodeId, sessionId, kind: "pty" };
+  }
+
+  async stopLiveAgent(projectId: string, agentId: string): Promise<StoppedLiveAgent> {
+    const list = this.getAgents(projectId);
+    if (!list.some((a) => a.id === agentId)) {
+      const err: GatewayError = {
+        code: "NOT_FOUND",
+        message: `agent ${agentId} not found in project ${projectId}`,
+      };
+      throw err;
+    }
+    const sessionId = this.liveSessionByAgent.get(agentId);
+    if (!sessionId) {
+      const err: GatewayError = {
+        code: "NOT_FOUND",
+        message: `agent ${agentId} has no live session`,
+      };
+      throw err;
+    }
+    const session = this.sessions.get(sessionId);
+    if (session) session.closed = true;
+    this.sessions.delete(sessionId);
+    this.liveSessionByAgent.delete(agentId);
+    this.liveByAgent.delete(agentId);
+    return { agentId, sessionId, kind: "pty" };
   }
 
   async createAgent(projectId: string, input: CreateAgentInput): Promise<Agent> {