add reusable options menu plugin with localized UI

- Settings autoloads (Game/Input/Graphics/Audio) backed by FileManager,
  persisted to user:// JSON files
- OptionsMenu scene with tabs wired to each autoload: Game (locale),
  Input (invert vertical axis), Graphics (window mode, borderless,
  screen), Audio (master/music/fx volume)
- GraphicsSettings reads DisplayServer state when running in editor
  to avoid clobbering the editor's window mode; exported builds load
  from disk and apply via set_screen_and_apply with a _loading guard
  to suppress redundant writes
- Built-in translations for en/es/fr/de/ja/zh_CN registered at runtime
  from translations/gd_options.csv
- Control-prompt icon assets for keyboard, PlayStation, Xbox, Nintendo
- Flesh out README with scope and audio bus layout requirement

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -1,3 +1,31 @@
 # gd-options
 
-re-usable settings plugin for godot (gd scripts), to configure game, graphics and sound settings.
+Re-usable settings/options menu for godot (gd scripts) to configure game, input, graphics and sound settings.
+
+- GameSettings global
+- InputSettings global
+- GraphicsSettings global
+- AudioSettings global
+- Saves and loads states from [user://](https://docs.godotengine.org/en/latest/tutorials/io/data_paths.html) application directory
+
+
+## Pre-Requisites
+
+Game:
+
+- TBD
+
+Input:
+
+- TBD
+
+Graphics:
+
+- TBD
+
+Audio:
+
+- Use the default_audio_bus_layout
+  - "Master" bus
+  - "Music" bus
+  - "FX" bus