fix(view-windows): réconcilier l'état des fenêtres détachées au boot (#50)

Branche le consommateur frontend sur la commande backend
`list_open_view_windows` : le port window expose la liste des fenêtres
de panneaux détachées réellement ouvertes côté OS, l'adaptateur Tauri
(et son double mock) l'implémente, et `ProjectsView` réconcilie le
placement des vues au démarrage à partir de ce snapshot au lieu de
supposer un état. Couvre `viewPlacement` et la réconciliation par des
tests dédiés.

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

frontend/src/adapters/mock/index.ts

@@ -90,6 +90,7 @@ import type {
   UpdateTicketInput,
   UiPreferencesGateway,
   ViewWindowClosed,
+  ViewWindowSnapshot,
   WindowGateway,
   FocusedProject,
   FocusedProjectGateway,
@@ -1118,6 +1119,16 @@ export class MockWindowGateway implements WindowGateway {
     }
   }
 
+  async listOpenViewWindows(): Promise<ViewWindowSnapshot[]> {
+    // Mirror the backend enumeration: every currently-open detached window is
+    // reported visible, with a stable label derived from its panel id.
+    return [...this.open].map((panel) => ({
+      panel,
+      label: panel,
+      visible: true,
+    }));
+  }
+
   async onViewWindowClosed(
     handler: (event: ViewWindowClosed) => void,
   ): Promise<Unsubscribe> {

frontend/src/adapters/window.ts

@@ -14,7 +14,11 @@ import { invoke } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 
 import type { Unsubscribe } from "@/domain";
-import type { ViewWindowClosed, WindowGateway } from "@/ports";
+import type {
+  ViewWindowClosed,
+  ViewWindowSnapshot,
+  WindowGateway,
+} from "@/ports";
 
 /** The single Tauri event carrying detached-window lifecycle transitions. */
 const VIEW_WINDOW_LIFECYCLE = "view-window://lifecycle";
@@ -41,6 +45,12 @@ export class TauriWindowGateway implements WindowGateway {
     await invoke("close_view_window", { panel });
   }
 
+  async listOpenViewWindows(): Promise<ViewWindowSnapshot[]> {
+    // Backend serialises the snapshots in camelCase (panel/label/visible), so the
+    // wire shape matches the port type directly.
+    return invoke<ViewWindowSnapshot[]>("list_open_view_windows");
+  }
+
   async onViewWindowClosed(
     handler: (event: ViewWindowClosed) => void,
   ): Promise<Unsubscribe> {