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>

assets/props/growler/textures/tx_growler_BC.tga.import

@@ -24,7 +24,7 @@ compress/rdo_quality_loss=0.0
 compress/hdr_compression=1
 compress/normal_map=0
 compress/channel_pack=0
-mipmaps/generate=false
+mipmaps/generate=true
 mipmaps/limit=-1
 roughness/mode=0
 roughness/src_normal=""
@@ -38,4 +38,4 @@ process/normal_map_invert_y=false
 process/hdr_as_srgb=false
 process/hdr_clamp_exposure=false
 process/size_limit=0
-detect_3d/compress_to=1
+detect_3d/compress_to=0

assets/props/growler/textures/tx_growler_NM.tga.import

@@ -24,7 +24,7 @@ compress/rdo_quality_loss=0.0
 compress/hdr_compression=1
 compress/normal_map=1
 compress/channel_pack=0
-mipmaps/generate=false
+mipmaps/generate=true
 mipmaps/limit=-1
 roughness/mode=0
 roughness/src_normal=""
@@ -38,4 +38,4 @@ process/normal_map_invert_y=false
 process/hdr_as_srgb=false
 process/hdr_clamp_exposure=false
 process/size_limit=0
-detect_3d/compress_to=1
+detect_3d/compress_to=0

assets/props/growler/textures/tx_growler_ORM.tga.import

@@ -24,7 +24,7 @@ compress/rdo_quality_loss=0.0
 compress/hdr_compression=1
 compress/normal_map=0
 compress/channel_pack=0
-mipmaps/generate=false
+mipmaps/generate=true
 mipmaps/limit=-1
 roughness/mode=0
 roughness/src_normal=""
@@ -38,4 +38,4 @@ process/normal_map_invert_y=false
 process/hdr_as_srgb=false
 process/hdr_clamp_exposure=false
 process/size_limit=0
-detect_3d/compress_to=1
+detect_3d/compress_to=0