feat(ui): fenêtres View système séparées — WebviewWindow Tauri + port WindowGateway (#23)

Détache les vues dans de vraies fenêtres système Tauri (multi-écran,
fullscreen). Backend : commandes de gestion de WebviewWindow, capabilities
et composition root. Frontend : nouveau port WindowGateway et son adaptateur
window, entrée panel-only ViewWindow/ViewPanelBody, détachement câblé dans
ProjectsView. QA vert : app-tauri 63, frontend typecheck + vitest 546/546.

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

frontend/src/features/projects/ViewPanelBody.tsx

@@ -0,0 +1,75 @@
+/**
+ * `ViewPanelBody` — renders the body of a single View panel from its id and a
+ * project context, reusing the existing feature panels as-is.
+ *
+ * Shared (ticket #23) between the in-window placements of {@link ProjectsView}
+ * (docked/floating) and the detached {@link ViewWindow} (its own OS window), so
+ * a view looks and behaves the same wherever it is placed. The `"projects"`
+ * panel is intentionally **not** handled here — the projects manager is
+ * main-window chrome, never a detachable view.
+ */
+
+import type { ReactNode } from "react";
+
+import { AgentsPanel } from "@/features/agents";
+import { TemplatesPanel } from "@/features/templates";
+import { SkillsPanel } from "@/features/skills";
+import { MemoryPanel } from "@/features/memory";
+import { EmbedderSettings } from "@/features/embedder";
+import { PermissionsPanel } from "@/features/permissions";
+import { ProjectWorkStatePanel } from "@/features/workstate";
+import { TicketsView } from "@/features/tickets";
+import { GitPanel } from "@/features/git";
+import { ProjectContextPanel } from "./ProjectContextPanel";
+import type { PanelId } from "./viewPlacement";
+
+/** Panels that render a project-scoped view (everything except "projects"). */
+export type ViewPanelId = Exclude<PanelId, "projects">;
+
+export interface ViewPanelBodyProps {
+  panel: ViewPanelId;
+  projectId: string;
+  /** Project root — required by the agents panel (its cwd base). */
+  projectRoot: string;
+  /** Optional: open a conversation viewer (only wired inside the main window). */
+  onOpenConversation?: (conversationId: string) => void;
+}
+
+/** Renders the requested view panel for the given project. */
+export function ViewPanelBody({
+  panel,
+  projectId,
+  projectRoot,
+  onOpenConversation,
+}: ViewPanelBodyProps): ReactNode {
+  switch (panel) {
+    case "context":
+      return <ProjectContextPanel projectId={projectId} />;
+    case "work":
+      return (
+        <ProjectWorkStatePanel
+          projectId={projectId}
+          onOpenConversation={onOpenConversation}
+        />
+      );
+    case "tickets":
+      return <TicketsView projectId={projectId} />;
+    case "agents":
+      return <AgentsPanel projectId={projectId} projectRoot={projectRoot} />;
+    case "templates":
+      return <TemplatesPanel projectId={projectId} />;
+    case "skills":
+      return <SkillsPanel projectId={projectId} />;
+    case "permissions":
+      return <PermissionsPanel projectId={projectId} />;
+    case "memory":
+      return (
+        <div className="flex flex-col gap-4">
+          <MemoryPanel projectId={projectId} />
+          <EmbedderSettings />
+        </div>
+      );
+    case "git":
+      return <GitPanel projectId={projectId} />;
+  }
+}