refactor: unify desktop apps and Settings under item catalog

programs/include/gui/desktop.hpp

@@ -18,15 +18,32 @@ namespace gui {
 static constexpr int MAX_WINDOWS = 32;
 static constexpr int PANEL_HEIGHT = 32;
 
-// External app discovered from 0:/apps/ manifest
-struct ExternalApp {
+enum DesktopItemSection : uint8_t {
+    DESKTOP_ITEM_SECTION_HIDDEN = 0,
+    DESKTOP_ITEM_SECTION_APPS,
+    DESKTOP_ITEM_SECTION_SETTINGS,
+};
+
+enum DesktopItemLaunchKind : uint8_t {
+    DESKTOP_ITEM_LAUNCH_EXECUTABLE = 0,
+    DESKTOP_ITEM_LAUNCH_BUILTIN,
+};
+
+// Launchable desktop item discovered from an app manifest or supplied by the
+// desktop's built-in registry.
+struct DesktopItem {
+    char id[48];
     char name[48];
     char binary_path[128];
     char icon_path[128];
     char category[24];
     SvgIcon icon;
+    DesktopItemSection section;
+    DesktopItemLaunchKind launch_kind;
+    int builtin_id;
     bool menu_visible;
     bool launch_with_home;
+    bool admin_only;
 };
 
 enum LauncherItemKind : uint8_t {
@@ -150,10 +167,10 @@ struct DesktopState {
 
     SvgIcon icon_volume;
 
-    // External apps discovered from 0:/apps/ manifests (dynamically grown)
-    ExternalApp* external_apps;
-    int external_app_count;
-    int external_app_capacity;
+    // Desktop items discovered from 0:/apps/ manifests (dynamically grown).
+    DesktopItem* desktop_items;
+    int desktop_item_count;
+    int desktop_item_capacity;
 
     bool ctx_menu_open;
     int ctx_menu_x, ctx_menu_y;

programs/include/gui/desktop_applet.hpp

@@ -1,37 +0,0 @@
-/*
-    * desktop_applet.hpp
-    * Shared-library desktop applet ABI for MontaukOS
-    * Copyright (c) 2026 Daniel Hammer
-*/
-
-#pragma once
-
-#include <cstdint>
-
-namespace gui::desktop_applet {
-
-inline constexpr uint32_t ABI_VERSION = 1;
-inline constexpr uint32_t CAP_SYSTEM_CONFIGURATION = 1u << 0;
-
-struct Host {
-    char current_user[32];
-    char home_dir[128];
-    char user_config_dir[128];
-    bool is_admin;
-};
-
-struct Descriptor {
-    uint32_t abi_version;
-    uint32_t capabilities;
-    const char* applet_id;
-    const char* display_name;
-    const char* icon_path;
-};
-
-using QueryFn = const Descriptor* (*)();
-using OpenFn = bool (*)(const Host* host);
-
-inline constexpr const char* QUERY_SYMBOL = "desktop_applet_query_v1";
-inline constexpr const char* OPEN_SYMBOL = "desktop_applet_open_v1";
-
-} // namespace gui::desktop_applet