Run godot --convert-3to4 (automated conversion)

Apply Godot 4.6 automated conversion: renames Spatial.translate->position,
margin_*->offset_*, tool->@tool, .empty()->.is_empty(), DynamicFont->FontFile,
onready->@onready, export()->@export, and many more.

127 files changed by the tool. Manual fixes still required for:
 - godot_db_manager plugin (incompatible APIs: WindowDialog, Tabs, etc.)
 - lod plugin (Spatial -> Node3D renames)
 - ResourceLoader.load_interactive removed -> load_threaded_request
 - OS.set_window_fullscreen removed -> DisplayServer
 - Viewport.set_size_override removed

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

assets/materials/gray.tres

@@ -32,7 +32,7 @@ void light() {
 "
 nodes/fragment/3/node = SubResource( 1 )
 nodes/fragment/3/position = Vector2( 0, 140 )
-nodes/fragment/connections = PoolIntArray( 3, 0, 0, 0 )
+nodes/fragment/connections = PackedInt32Array( 3, 0, 0, 0 )
 
 [resource]
 shader = SubResource( 2 )