feat(agents): role orchestrateur du contexte global expose et configurable par agent — isOrchestrator distinct des permissions MCP, DTO update_project_orchestrator (terminologie wire legacy conservee), refus idea_context_update explicite avec writer effectif + orientation idea_context_propose, surface AgentsPanel + adaptateurs frontend — #276 (QA verte: cargo fmt/check, tests cibles application/app-tauri/infrastructure/backend, npm typecheck, 69/69 tests frontend agents/adapters)

frontend/src/adapters/mock/index.ts

@@ -720,6 +720,24 @@ export class MockAgentGateway implements AgentGateway {
     return structuredClone(list[idx]);
   }
 
+  async updateProjectOrchestrator(
+    projectId: string,
+    agentId: string,
+  ): Promise<{ orchestratorAgentId: string }> {
+    const list = this.getAgents(projectId);
+    if (!list.some((agent) => agent.id === agentId)) {
+      const err: GatewayError = {
+        code: "NOT_FOUND",
+        message: `agent ${agentId} not found in project ${projectId}`,
+      };
+      throw err;
+    }
+    for (let index = 0; index < list.length; index += 1) {
+      list[index] = { ...list[index], isOrchestrator: list[index].id === agentId };
+    }
+    return { orchestratorAgentId: agentId };
+  }
+
   // ── Internal helpers for MockTemplateGateway (same-package use only) ──
 
   /**