Tool windows redesign and the Novel Editor workspace

Tool windows:
- Every editor (scenario, scene builder, map, interactive objects,
  lighting, catalog export) is rebuilt on the interface ToolWindow chrome
  and the denser ToolTheme: header with title/close, status bar, Ctrl+S,
  dirty-state confirmation.
- Shared building blocks in src/Common: ToolUi (rows, buttons, sections),
  CollapsibleSection, FilteredList, ModFileSelector, DragHandle and
  BackgroundCanvas (scene background with pan/zoom).
- The map, interactive and light editors draw on canvases
  (MapEditorCanvas, InteractiveEditorCanvas, LightEditorCanvas) instead of
  one Control "handle" node per object; the *Handle classes are removed.
- Scenario editor: tab data model (TabData), automatic graph layout
  (ScenarioGraphLayout), file tree/info/thumbnail panel updates.
- Services: ModFileService (mod file listing and writing),
  SceneBackgroundService; MapFileService/ModResourceService follow.
- Catalog export: per-language name/description editing.
- Locale (en/ru) regrouped under tools/*; unused keys removed.

Novel Editor:
- collections/novel_editor.json: a "game" whose entry scene is an
  authoring workspace over the novel engine and the story content.
- NovelEditorHub (scenes/novel_editor_hub.tscn) lists every installed
  tool through IToolProvider.AddMenuButton; ToolsInitializer registers it
  as the logical scene "novel_editor".

src/Hub/ToolsInitializer.cs

@@ -0,0 +1,26 @@
+namespace Cthangover.Tools.Hub
+{
+    using Cthangover.Core.Mods;
+    using Cthangover.Core.Scenes;
+
+    /// <summary>
+    /// Lifecycle entry point of the tools mod. Publishes the logical scene
+    /// <see cref="NovelEditorHub.SceneName"/>, the entry scene of the
+    /// <c>novel_editor</c> collection: launching that collection from the game
+    /// picker goes through the regular new-game flow and lands on the editor
+    /// launcher instead of a story scene.
+    /// </summary>
+    public class ToolsInitializer : IModInitializer
+    {
+        private const string HubScenePath = "scenes/novel_editor_hub.tscn";
+
+        public void OnModLoaded(string modId)
+        {
+        }
+
+        public void OnModResourcesReady()
+        {
+            SceneRouteRegistry.Register(NovelEditorHub.SceneName, HubScenePath, fade: false);
+        }
+    }
+}