fix(levels): ScenePath must be a string, not a PackedScene

slice 7 regression. level_village_2..5.tscn each reference their own
LevelResource for the death screen label, so pointing the resource back
at the scene forms a cycle Godot cannot resolve - "Parse Error: Busy"
and the level fails to load entirely.

ScenePath was a string for exactly this reason. Reverted, and the rot it
allowed (forest_1 aimed at a nonexistent scene) is now caught by
LevelCatalogue.Validate checking every path resolves, plus a repo-level
structural check - fixed by validation rather than by typing.

project.godot: restores the C# feature flag and dialogue_manager
uses_dotnet, which `godot --headless --import` strips on every run.

resources/levels/level_catalogue.tres

@@ -1,6 +1,6 @@
 [gd_resource type="Resource" script_class="LevelCatalogue" load_steps=8 format=3]
 
-[ext_resource type="Script" path="res://scripts/Resources/LevelCatalogue.cs" id="1_script"]
+[ext_resource type="Script" uid="uid://cxryfiktqs7s1" path="res://scripts/Resources/LevelCatalogue.cs" id="1_script"]
 [ext_resource type="Resource" path="res://resources/levels/tutorial_1.tres" id="2_tutorial_1"]
 [ext_resource type="Resource" uid="uid://cqtalsov2bkpo" path="res://resources/levels/village/village_1.tres" id="3_village_1"]
 [ext_resource type="Resource" uid="uid://dlwkbjw1l33uq" path="res://resources/levels/village/village_2.tres" id="4_village_2"]