Make Main, Settings, ChooseScene, and gameplay run in Godot 4.6

Catch-all commit for everything the --convert-3to4 tool missed during a
manual playtest of the game. All errors raised by clicking through Main
-> Puzzles -> level were fixed.

GDScript:
- PackedScene.instance() -> instantiate() (ChooseScene.gd)
- String(x) constructor doesn't exist -> str(x) (MBase, MScene,
  MLevel, Animation, Levels)
- 'x as int/String/bool' doesn't parse strings -> explicit
  int()/str()/bool(int()) (MScene, MLevel, MSetting)
- BaseButton.pressed (property) -> button_pressed; set_pressed() ->
  direct assignment (Settings.gd)
- AnimationPlayer.add_animation() removed -> go through
  AnimationLibrary (Levels.gd)
- PhysicsDirectSpaceState3D.intersect_ray(from, to, ...) ->
  PhysicsRayQueryParameters3D.create() (Levels.gd)
- @export with type-hint-in-comment ('# (String, ...)') -> explicit
  @export_enum (candle.gd)
- Get effective material with get_active_material() instead of
  get_surface_override_material(), with null guard (Levels.gd)
- get_node() -> get_node_or_null() so missing items from ahog.json
  (e.g. sm_super_dager in Home) don't crash (Levels.gd)

Scenes/resources:
- Remove 14 Tween nodes from WarCraft.tscn — Tween is no longer a
  Node in Godot 4. Rewrite Animation.start_dissolve to use
  create_tween().tween_method().
- Rename property material/N -> surface_material_override/N in every
  .tscn (10 files) — Godot 3 -> 4 rename that --convert-3to4 missed.
  Without this, MeshInstance3D.get_active_material(0) returned the
  glTF-imported StandardMaterial3D instead of the project's custom
  dissolve ShaderMaterial.

Shaders:
- One-shot scripts/migrate_shaders.gd walks every .material under
  assets/ and fixes Godot 3 -> 4 shader code in-place. Fixed 17
  materials: depth_draw_alpha_prepass -> depth_prepass_alpha,
  hint_color -> source_color, NORMALMAP -> NORMAL_MAP.

Result: Main, Settings, ChooseScene, and the WarCraft level all run
without script or shader errors. Remaining noise is non-blocking
(visual_shader graph in text_outline.material, baked lightmap binary
format from Godot 3, and empty animation tracks).

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

scripts/Animation.gd

@@ -5,7 +5,7 @@ var current_material = null
 func level_hud_slide(node):
 	var animation = Animation.new()
 	var track_index = animation.add_track(Animation.TYPE_BEZIER)
-	var node_element = String(node.get_path()) + ":position:x"
+	var node_element = str(node.get_path()) + ":position:x"
 	
 	animation.track_set_path(track_index, node_element)
 	animation.bezier_track_insert_key(track_index, 0.0, 0.0, Vector2(-0.25, 0), Vector2(0.031, 190.492))
@@ -16,7 +16,7 @@ func level_hud_slide(node):
 func level_hud_warning(node):
 	var animation = Animation.new()
 	var track_index = animation.add_track(Animation.TYPE_BEZIER)
-	var node_element = String(node.get_path()) + ":position:x"
+	var node_element = str(node.get_path()) + ":position:x"
 	
 	animation.track_set_path(track_index, node_element)
 	animation.bezier_track_insert_key(track_index, 0.0, 0.0, Vector2(-0.25, 0), Vector2(0, 78.1))
@@ -29,9 +29,15 @@ func level_hud_warning(node):
 	return animation
 
 func start_dissolve(node, material):
+	if material == null:
+		return
 	current_material = material
-	node.interpolate_method(self, "animate_dissolve", 0, 1, 1.5, Tween.TRANS_LINEAR, Tween.EASE_IN_OUT)
-	node.start()
+	var tween = node.create_tween()
+	tween.tween_method(animate_dissolve, 0.0, 1.0, 1.5) \
+		.set_trans(Tween.TRANS_LINEAR) \
+		.set_ease(Tween.EASE_IN_OUT)
 
 func animate_dissolve(progress: float) -> void:
+	if current_material == null:
+		return
 	current_material.set_shader_parameter("dissolve_amount", ease(progress, 0.4))