feat(a2a): Godot 4.7 .NET project scaffold referencing Age.Engine (headless smoke)

SMOKE: Paths resolves to age-reimpl inside Godot; Age.Engine parses SC0000 in-process.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

godot/Main.cs

@@ -0,0 +1,14 @@
+using Godot;
+using Age.Engine.Sys4;
+
+public partial class Main : Godot.Control
+{
+    public override void _Ready()
+    {
+        var table = OpcodeTableJson.Load(Paths.OpcodesJson);
+        var script = Sys4Loader.Load(Paths.Scripts()["SC0000.BIN"], table);
+        GD.Print($"SMOKE repo={Paths.Repo}");
+        GD.Print($"SMOKE SC0000 instrs={script.Instructions.Count} strings={script.Strings.Count}");
+        GetTree().Quit(0);
+    }
+}