fix(windows): fenêtres de panneau détachées suivent le projet en focus côté UI (#47)

Partie frontend. Ajoute un adaptateur focusedProject et un port dédié : la
ViewWindow détachée n'est plus liée à un project_id figé, elle s'abonne à
l'event focused-project émis par la fenêtre principale et affiche le panneau
du projet courant. ProjectsView propage le focus ; le détachement crée une
fenêtre panel-only. Couvert par les tests window/ViewWindow/focusedProject/
ProjectsView.focus.

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

frontend/src/adapters/mock/index.ts

@@ -91,6 +91,8 @@ import type {
   UiPreferencesGateway,
   ViewWindowClosed,
   WindowGateway,
+  FocusedProject,
+  FocusedProjectGateway,
   WorkStateGateway,
 } from "@/ports";
 import { normalizeProjectWorkState } from "../workStateNormalization";
@@ -1094,27 +1096,25 @@ class MockRemoteGateway implements RemoteGateway {
 }
 
 /**
- * In-memory {@link WindowGateway} for tests/dev (#23). Tracks which views are
- * "detached" in a set keyed by `panel|projectId`, and lets tests simulate the
- * OS closing a window via {@link simulateOsClose}. `closeViewWindow` also emits
- * the close event, mirroring the backend (a programmatic close still notifies).
+ * In-memory {@link WindowGateway} for tests/dev (#23, panel-only in #47). Tracks
+ * which views are "detached" in a set keyed by `panel` alone (a panel-only
+ * window follows the focused project, so no project id is part of the key), and
+ * lets tests simulate the OS closing a window via {@link simulateOsClose}.
+ * `closeViewWindow` also emits the close event, mirroring the backend (a
+ * programmatic close still notifies).
  */
 export class MockWindowGateway implements WindowGateway {
-  /** Currently-open detached windows, keyed `panel|projectId`. */
+  /** Currently-open detached windows, keyed by `panel`. */
   readonly open = new Set<string>();
   private readonly listeners = new Set<(e: ViewWindowClosed) => void>();
 
-  private key(panel: string, projectId: string): string {
-    return `${panel}|${projectId}`;
+  async openViewWindow(panel: string): Promise<void> {
+    this.open.add(panel);
   }
 
-  async openViewWindow(panel: string, projectId: string): Promise<void> {
-    this.open.add(this.key(panel, projectId));
-  }
-
-  async closeViewWindow(panel: string, projectId: string): Promise<void> {
-    if (this.open.delete(this.key(panel, projectId))) {
-      this.emit({ panel, projectId });
+  async closeViewWindow(panel: string): Promise<void> {
+    if (this.open.delete(panel)) {
+      this.emit({ panel });
     }
   }
 
@@ -1128,9 +1128,9 @@ export class MockWindowGateway implements WindowGateway {
   }
 
   /** Test hook: simulate the user closing the OS window (fires the event). */
-  simulateOsClose(panel: string, projectId: string): void {
-    this.open.delete(this.key(panel, projectId));
-    this.emit({ panel, projectId });
+  simulateOsClose(panel: string): void {
+    this.open.delete(panel);
+    this.emit({ panel });
   }
 
   private emit(event: ViewWindowClosed): void {
@@ -1138,6 +1138,38 @@ export class MockWindowGateway implements WindowGateway {
   }
 }
 
+/**
+ * In-memory {@link FocusedProjectGateway} for tests/dev (#47). Holds the current
+ * focus in memory and fans changes out to subscribers — the mock counterpart to
+ * the backend's shared focused-project state + `focused-project://changed`
+ * event. `setFocusedProject` always notifies (mirrors the backend emit), so a
+ * detached-window test can drive a panel window's focus transitions.
+ */
+export class MockFocusedProjectGateway implements FocusedProjectGateway {
+  private focused: FocusedProject | null = null;
+  private readonly listeners = new Set<
+    (project: FocusedProject | null) => void
+  >();
+
+  async setFocusedProject(project: FocusedProject | null): Promise<void> {
+    this.focused = project;
+    for (const l of this.listeners) l(project);
+  }
+
+  async getFocusedProject(): Promise<FocusedProject | null> {
+    return this.focused;
+  }
+
+  async onFocusedProjectChanged(
+    handler: (project: FocusedProject | null) => void,
+  ): Promise<Unsubscribe> {
+    this.listeners.add(handler);
+    return () => {
+      this.listeners.delete(handler);
+    };
+  }
+}
+
 /**
  * The pre-filled reference catalogue the mock serves — mirror of the backend's
  * **selectable** catalogue (§17.3/D7): only profiles drivable in structured mode
@@ -2596,6 +2628,7 @@ export function createMockGateways(): Gateways {
     conversation: new MockConversationGateway(),
     ticket: new MockTicketGateway(systemGateway),
     window: new MockWindowGateway(),
+    focusedProject: new MockFocusedProjectGateway(),
     uiPreferences: new MockUiPreferencesGateway(),
   };
 }

frontend/src/adapters/mock/mock.test.ts

@@ -17,6 +17,7 @@ describe("createMockGateways", () => {
       "agent",
       "conversation",
       "embedder",
+      "focusedProject",
       "git",
       "input",
       "layout",