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".

scenes/novel_editor_hub.tscn

@@ -0,0 +1,12 @@
+[gd_scene format=3]
+
+[ext_resource type="Script" path="src/Hub/NovelEditorHub.cs" id="NovelEditorHubScript"]
+
+[node name="NovelEditorHub" type="Control"]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("NovelEditorHubScript")

scenes/scenario_file_tree_panel.tscn

@@ -5,6 +5,10 @@
 [node name="ScenarioFileTreePanel" type="VBoxContainer" script=ExtResource("1_script")]
 size_flags_horizontal = 3
 size_flags_vertical = 3
+theme_override_constants/separation = 4
+
+[node name="Search" type="LineEdit" parent="."]
+clear_button_enabled = true
 
 [node name="FileTree" type="Tree" parent="."]
 size_flags_horizontal = 3

scenes/scenario_info_panel.tscn

@@ -9,10 +9,11 @@ theme_override_constants/separation = 6
 
 [node name="Scroll" type="ScrollContainer" parent="."]
 size_flags_vertical = 3
-horizontal_scroll_mode = 3
+horizontal_scroll_mode = 0
 
 [node name="VBox" type="VBoxContainer" parent="Scroll"]
-theme_override_constants/separation = 8
+size_flags_horizontal = 3
+theme_override_constants/separation = 4
 
 [node name="HintScene" type="Label" parent="Scroll/VBox"]