Add comprehensive tests and optimizations for simulation and UI performance

- Introduced a new benchmark save script to create a stress test scenario with extreme values for simulation performance.
- Added a full UI benchmark script to measure frame rates and performance metrics during UI interactions.
- Implemented tests for coarse generations to ensure population transitions are handled correctly.
- Created tests for extra parameters to validate the loading and application of configuration settings.
- Developed simulation optimization tests to verify the efficiency of population drift and rounding mechanisms.
- Added split optimization tests to ensure accurate allocation and rounding behavior in population management.
- Included startup parameter tests to confirm the correct initialization of global parameters before scene readiness.
- Enhanced the audit rounding ledger to compare selective and full rounding results for consistency.

ui/main_menu/main_menu.gd

@@ -7,6 +7,8 @@ const SILENT_VOLUME_DB := -80.0
 @onready var music_button: TextureButton = $Media/Music
 @onready var sound_volume: HSlider = $Volume/SoundVolume
 @onready var music_volume: HSlider = $Volume/MusicVolume
+@onready var english_button: TextureButton = $Language/English
+@onready var russian_button: TextureButton = $Language/Russian
 @onready var effects_player: OwniverseEffectsPlayer = $"../../FXPlayer"
 @onready var music_player: OwniverseMusicPlayer = $"../../MusicPlayer"
 
@@ -17,6 +19,7 @@ func _ready() -> void:
     music_button.set_pressed_no_signal(bool(Global.Settings.music_enabled))
     sound_volume.set_value_no_signal(float(Global.Settings.sound_volume) * sound_volume.max_value)
     music_volume.set_value_no_signal(float(Global.Settings.music_volume) * music_volume.max_value)
+    _update_locale_buttons()
     _apply_sound_settings()
     _apply_music_settings()
 
@@ -65,3 +68,14 @@ func _apply_bus_volume(bus_name: String, value: float) -> void:
     var normalized: float = clampf(value, 0.0, 1.0)
     var volume_db: float = SILENT_VOLUME_DB if is_zero_approx(normalized) else lerpf(MIN_VOLUME_DB, 0.0, normalized)
     AudioServer.set_bus_volume_db(bus_index, volume_db)
+
+
+func _on_change_locale_pressed(locale: String) -> void:
+    Global.set_locale(locale)
+    _update_locale_buttons()
+    SaveManager.save_settings()
+
+
+func _update_locale_buttons() -> void:
+    english_button.set_pressed_no_signal(Global.Locale == "en")
+    russian_button.set_pressed_no_signal(Global.Locale == "ru")