feat(frontend): host les fenêtres plugin et l'API publique windows.open

Ajoute la vue window host qui charge le layout plugin dans une fenêtre OS
détachée, expose react/react-dom/jsx-runtime hébergés sous
frontend/public/plugin-host pour que le runtime SDK y résolve React, et
câble services.windows.open() côté runtime plugin (loader/services/registry).

npm test -- --run src/adapters/window.test.ts src/app/ViewWindow.test.tsx
  src/plugins/runtime/loader.test.ts src/plugins/runtime/services.test.ts : 39/39
npm run typecheck : OK
npm run build : OK

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

frontend/src/adapters/http/unsupported.ts

@@ -79,6 +79,9 @@ export class WebWindowGateway implements WindowGateway {
   openViewWindow(): Promise<void> {
     return unsupportedOnWeb("Detaching a panel into an OS window");
   }
+  openPluginLayoutWindow(): Promise<never> {
+    return unsupportedOnWeb("Opening a plugin layout in an OS window");
+  }
   closeViewWindow(): Promise<void> {
     return unsupportedOnWeb("Closing a detached OS window");
   }

frontend/src/adapters/mock/index.ts

@@ -162,6 +162,8 @@ import type {
   ViewWindowClosed,
   ViewWindowSnapshot,
   WindowGateway,
+  PluginLayoutWindowOpenInput,
+  PluginLayoutWindowOpenResult,
   FocusedProject,
   FocusedProjectGateway,
   WorkStateGateway,
@@ -1284,12 +1286,34 @@ class MockRemoteGateway implements RemoteGateway {
 export class MockWindowGateway implements WindowGateway {
   /** Currently-open detached windows, keyed by `panel`. */
   readonly open = new Set<string>();
+  readonly pluginLayoutWindows = new Map<string, PluginLayoutWindowOpenResult>();
   private readonly listeners = new Set<(e: ViewWindowClosed) => void>();
 
   async openViewWindow(panel: string): Promise<void> {
     this.open.add(panel);
   }
 
+  async openPluginLayoutWindow(
+    input: PluginLayoutWindowOpenInput,
+  ): Promise<PluginLayoutWindowOpenResult> {
+    const label = `view-plugin-layout-${input.pluginId}.${input.layoutType}`;
+    const alreadyOpen = this.pluginLayoutWindows.has(label);
+    const result: PluginLayoutWindowOpenResult = {
+      label,
+      url: `index.html?pluginLayout=1&pluginId=${encodeURIComponent(input.pluginId)}&layoutType=${encodeURIComponent(input.layoutType)}`,
+      alreadyOpen,
+      providerPluginDisplayName: input.pluginId,
+      layoutLabel: input.layoutType,
+      surface: {
+        pluginId: input.pluginId,
+        layoutType: input.layoutType,
+        state: input.state ?? null,
+      },
+    };
+    this.pluginLayoutWindows.set(label, result);
+    return result;
+  }
+
   async closeViewWindow(panel: string): Promise<void> {
     if (this.open.delete(panel)) {
       this.emit({ panel });

frontend/src/adapters/window.test.ts

@@ -29,6 +29,41 @@ describe("TauriWindowGateway (#23)", () => {
     });
   });
 
+  it("opens plugin layout windows through the backend command", async () => {
+    invoke.mockResolvedValueOnce({
+      label: "view-plugin-layout",
+      url: "index.html?pluginLayout=1",
+      alreadyOpen: false,
+      providerPluginDisplayName: "Plugin",
+      layoutLabel: "Dashboard",
+      surface: {
+        pluginId: "dev.acme.plugin",
+        layoutType: "dev.acme.plugin.dashboard",
+        state: { tab: "overview" },
+      },
+    });
+    const gw = new TauriWindowGateway();
+
+    await expect(
+      gw.openPluginLayoutWindow({
+        pluginId: "dev.acme.plugin",
+        layoutType: "dev.acme.plugin.dashboard",
+        state: { tab: "overview" },
+      }),
+    ).resolves.toMatchObject({
+      label: "view-plugin-layout",
+      surface: { layoutType: "dev.acme.plugin.dashboard" },
+    });
+
+    expect(invoke).toHaveBeenCalledWith("open_plugin_layout_window", {
+      input: {
+        pluginId: "dev.acme.plugin",
+        layoutType: "dev.acme.plugin.dashboard",
+        state: { tab: "overview" },
+      },
+    });
+  });
+
   it("onViewWindowClosed listens on the lifecycle channel and forwards only closes", async () => {
     // Capture the raw Tauri listener so we can drive lifecycle events at will.
     let raw: ((e: { payload: unknown }) => void) | undefined;

frontend/src/adapters/window.ts

@@ -15,6 +15,8 @@ import { listen } from "@tauri-apps/api/event";
 
 import type { Unsubscribe } from "@/domain";
 import type {
+  PluginLayoutWindowOpenInput,
+  PluginLayoutWindowOpenResult,
   ViewWindowClosed,
   ViewWindowSnapshot,
   WindowGateway,
@@ -41,6 +43,14 @@ export class TauriWindowGateway implements WindowGateway {
     await invoke("open_view_window", { panel });
   }
 
+  async openPluginLayoutWindow(
+    input: PluginLayoutWindowOpenInput,
+  ): Promise<PluginLayoutWindowOpenResult> {
+    return invoke<PluginLayoutWindowOpenResult>("open_plugin_layout_window", {
+      input,
+    });
+  }
+
   async closeViewWindow(panel: string): Promise<void> {
     await invoke("close_view_window", { panel });
   }