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/workState.ts

@@ -0,0 +1,17 @@
+/**
+ * Tauri adapter for {@link WorkStateGateway}.
+ *
+ * This is the only frontend place that knows the `get_project_work_state`
+ * command name; features consume the gateway port through DI.
+ */
+
+import { invoke } from "@tauri-apps/api/core";
+
+import type { ProjectWorkState } from "@/domain";
+import type { WorkStateGateway } from "@/ports";
+
+export class TauriWorkStateGateway implements WorkStateGateway {
+  getProjectWorkState(projectId: string): Promise<ProjectWorkState> {
+    return invoke<ProjectWorkState>("get_project_work_state", { projectId });
+  }
+}