Replace Event + GlobalAnimation autoloads with class_name + static funcs

Two of the five autoloads were stateless helper bundles, not the
persistent application-wide systems that the Godot 4 best-practice
guide reserves autoload slots for. Convert them to plain classes with
all-static methods so they no longer need a Node living under /root.

- scripts/Animation.gd -> scripts/game_animation.gd (renamed:
  conflict with the built-in Animation class; the autoload sidestepped
  it by being called GlobalAnimation). class_name GameAnimation,
  every helper static. The dissolve tween now captures its target
  material in a lambda closure, eliminating the current_material
  member that the autoload kept as shared mutable state.
- scripts/Event.gd -> scripts/event.gd, class_name Event, every
  handler static. Added Event.level_pressed(name) -> Callable for the
  one place ChooseScene needed dynamic lookup of a per-level handler
  (replaces the old _build_method('_on_' + name + '_pressed') +
  Callable(autoload, string) reflection trick with an explicit match).

Updated call sites:
- scripts/Global.gd: animation.connect('animation_started',
  Callable(Event, '...')) -> animation.animation_started.connect(
  Event._loading_is_started). Same for animation_finished.
- scenes/levels/Levels.gd: GlobalAnimation.* -> GameAnimation.*;
  Quit/TextureButton.connect('pressed', Callable(Event, '...')) ->
  pressed.connect(Event._on_main_scene_pressed).
- scenes/UI/choose_scenes/ChooseScene.gd: per-level button connects
  go through Event.level_pressed(); reset button's bound callable now
  reads Event._on_reset_level.bind(...); cleanup no longer relies on
  is_connected with an unbound Callable (which would never match a
  bound one anyway) -- iterates reset.pressed.get_connections()
  instead. Drop the now-dead _build_method helper.

Also: organise scripts/ by promoting the one-shot migration helpers
(migrate_shaders, migrate_misc, resave_scenes, devisualize_shaders,
find_visualshaders) into scripts/migration/. They are not part of
the runtime and should not be browsable next to the autoloads.

Autoload count goes 5 -> 3 (Loading, Global, Setting remain --
Setting will move to a Resource in a later refactor).

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

scripts/event.gd

@@ -0,0 +1,42 @@
+class_name Event
+
+# UI event handlers, namespaced as static methods so they can be wired
+# directly from anywhere without an autoload.
+#
+#   button.pressed.connect(Event._on_main_scene_pressed)
+#
+# Per-level dispatch goes through `level_pressed(name)` which maps the level
+# name to the appropriate handler.
+
+static func _loading_is_started(_anim_name: StringName) -> void:
+	Global.loaded = false
+
+static func _loading_is_finished(_anim_name: StringName) -> void:
+	Global.loaded = true
+
+static func _on_warcraft_pressed() -> void:
+	Global.current_scene_int = 0
+	Global.goto_scene("res://scenes/levels/warcraft/WarCraft.tscn")
+
+static func _on_home_pressed() -> void:
+	Global.current_scene_int = 1
+	Global.goto_scene("res://scenes/levels/home/Home.tscn")
+
+static func _on_reset_level(level, node: String, index: int, parent) -> void:
+	Global.current_scene_int = index
+	level.reset()
+	parent.configure_reset(level, node, index, true)
+	parent.configure_counter(level, node)
+	Global.current_scene_int = null
+
+static func _on_main_scene_pressed() -> void:
+	Global.goto_scene("res://scenes/Main.tscn")
+
+# Returns the press handler for a level by name (used by ChooseScene to wire
+# the dynamic level-select buttons). Returns Callable() if unknown.
+static func level_pressed(name: String) -> Callable:
+	match name.to_lower():
+		"warcraft": return _on_warcraft_pressed
+		"home": return _on_home_pressed
+	push_warning("Event.level_pressed: no handler for level '%s'" % name)
+	return Callable()