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/agent.ts

@@ -154,6 +154,16 @@ export class TauriAgentGateway implements AgentGateway {
     });
   }
 
+  updateProjectOrchestrator(
+    projectId: string,
+    agentId: string,
+  ): Promise<{ orchestratorAgentId: string }> {
+    return invoke<{ orchestratorAgentId: string }>(
+      "update_project_orchestrator",
+      { request: { projectId, agentId } },
+    );
+  }
+
   readContext(projectId: string, agentId: string): Promise<string> {
     return invoke<AgentContextDocument>("read_agent_context", {
       projectId,