feat(workstate): UI live-state des conversations/délégations (Lot A frontend)

Ajoute le port et l'adaptateur workState (+ mock) côté frontend, le type domaine
associé, et la feature `workstate` (panneau ProjectWorkStatePanel + hook
useProjectWorkState) consommant le read-model live exposé par le backend.
Intègre le panneau dans ProjectsView. Tests verts (workstate + projects).

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

frontend/src/adapters/mock/index.ts

@@ -31,6 +31,7 @@ import type {
   PermissionSet,
   Project,
   ProjectPermissions,
+  ProjectWorkState,
   ProfileAvailability,
   ResumableAgent,
   Skill,
@@ -64,6 +65,7 @@ import type {
   TemplateGateway,
   TerminalGateway,
   TerminalHandle,
+  WorkStateGateway,
 } from "@/ports";
 import { applyOperation, singleLeafTree } from "@/features/layout/layout";
 
@@ -1648,6 +1650,19 @@ export class MockPermissionGateway implements PermissionGateway {
   }
 }
 
+export class MockWorkStateGateway implements WorkStateGateway {
+  private states = new Map<string, ProjectWorkState>();
+
+  /** Seeds the read-model returned for a project (deterministic tests/dev). */
+  _setProjectWorkState(projectId: string, state: ProjectWorkState): void {
+    this.states.set(projectId, structuredClone(state));
+  }
+
+  async getProjectWorkState(projectId: string): Promise<ProjectWorkState> {
+    return structuredClone(this.states.get(projectId) ?? { agents: [] });
+  }
+}
+
 function mostRestrictive(
   project?: PermissionSet["fallback"],
   agent?: PermissionSet["fallback"],
@@ -1676,6 +1691,7 @@ export function createMockGateways(): Gateways {
     memory: new MockMemoryGateway(),
     embedder: new MockEmbedderGateway(),
     permission: new MockPermissionGateway(),
+    workState: new MockWorkStateGateway(),
   };
 }