M0: Scaffold Theriapolis.Godot project (hello-world)

First milestone of the Godot port. Establishes the new project structure
and verifies the toolchain is wired up end-to-end.

- Godot.NET.Sdk/4.6.2 targeting net8.0; references Theriapolis.Core
- project.godot configured for borderless fullscreen at native resolution
  (per port plan §10 resolved decisions); F11 toggles to windowed
- Main.tscn + Main.cs hello-world; nearest-neighbor texture filtering
- icon.svg placeholder (T in gild on dark)
- Added to Theriapolis.sln

Verification:
- dotnet build Theriapolis.Godot.csproj: 0 errors, 0 warnings
- dotnet build Theriapolis.sln: 0 errors (6 pre-existing warnings unrelated)
- dotnet test: 708/708 pass in 26s (unchanged from master)
- Godot 4.6.2 opens project; fullscreen + F11 toggle confirmed visually

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Theriapolis.Godot/project.godot

@@ -0,0 +1,39 @@
+; Engine configuration file.
+; Generated for Theriapolis Godot port (M0).
+;
+; Format documentation: https://docs.godotengine.org/en/stable/classes/class_projectsettings.html
+
+config_version=5
+
+[application]
+
+config/name="Theriapolis"
+config/description="Theriapolis — TTRPG worldgen + simulation game (Godot port)."
+run/main_scene="res://Main.tscn"
+config/features=PackedStringArray("4.6", "C#", "Forward Plus")
+config/icon="res://icon.svg"
+
+[display]
+
+; Borderless fullscreen at the primary monitor's native resolution
+; (per port plan §10 resolved decisions). F11 toggles to windowed.
+window/size/mode=3
+window/stretch/mode="canvas_items"
+window/stretch/aspect="expand"
+
+[dotnet]
+
+project/assembly_name="Theriapolis.Godot"
+
+[input]
+
+ui_toggle_fullscreen={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":-1,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":4194342,"physical_keycode":0,"key_label":0,"unicode":0,"location":0,"echo":false,"script":null)
+]
+}
+
+[rendering]
+
+renderer/rendering_method="forward_plus"
+textures/canvas_textures/default_texture_filter=0