feat: deliver the redesigned desktop workspace

Rebuild downloads, link collection, settings, history, and statistics around a responsive desktop shell with compact account and queue tables, contextual navigation, persistent update affordances, unified overlays, and accessible keyboard interactions.

Add safe history-folder reveal IPC, responsive 2560/1920/1366/1120 coverage, deterministic visual fixtures, focused component regressions, and release-tree exclusions for internal working files. Bump the public application version to 2.0.13.

src/renderer/shell/shell-model.ts

@@ -0,0 +1,39 @@
+import type { IconName } from "../ui/Icon";
+
+export type MainView = "downloads" | "collector" | "settings" | "history" | "statistics";
+export type ResponsiveShellMode = "full" | "compact" | "minimum";
+
+export interface NavigationItem {
+  id: MainView;
+  label: string;
+  icon: IconName;
+  active: boolean;
+}
+
+const MAIN_NAVIGATION = [
+  { id: "downloads", label: "Downloads", icon: "download" },
+  { id: "collector", label: "Linksammler", icon: "collector" },
+  { id: "settings", label: "Einstellungen", icon: "settings" },
+  { id: "history", label: "Verlauf", icon: "history" },
+  { id: "statistics", label: "Statistiken", icon: "statistics" }
+] as const;
+
+export function buildMainNavigation(active: MainView): NavigationItem[] {
+  return MAIN_NAVIGATION.map((item) => ({ ...item, active: item.id === active }));
+}
+
+export function getMainViewLabel(view: MainView): string {
+  return MAIN_NAVIGATION.find((item) => item.id === view)?.label ?? view;
+}
+
+export function getResponsiveShellMode(width: number): ResponsiveShellMode {
+  if (width <= 1120) {
+    return "minimum";
+  }
+
+  if (width <= 1366) {
+    return "compact";
+  }
+
+  return "full";
+}