Add project skeleton: Godot setup, tooling, and smoke test

Pins Godot 4.6.3-stable and GUT 9.6.0 (9.6.1+ reference
AccessibilityServer, unavailable in 4.6.3) via tools/setup.sh. Wires
make check (gdlint + gdformat config for 4-space indent, headless
GUT run, and a JSON well-formedness check ahead of real schema
validation). Seven autoload stubs match the architecture in the
cahier des charges; real logic lands with the following steps.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Makefile

@@ -0,0 +1,35 @@
+GODOT_BIN := .godot-bin/godot
+VENV := .venv
+GDLINT := $(VENV)/bin/gdlint
+GDFORMAT := $(VENV)/bin/gdformat
+GD_SOURCES := autoload scripts tests
+
+.PHONY: setup run lint format validate-data test check export-linux export-windows
+
+setup:
+	tools/setup.sh
+
+run:
+	$(GODOT_BIN) --path .
+
+lint:
+	$(GDLINT) $(GD_SOURCES)
+
+format:
+	$(GDFORMAT) $(GD_SOURCES)
+
+validate-data:
+	$(GODOT_BIN) --headless --path . -s res://scripts/data/validate_data_cli.gd
+
+test:
+	$(GODOT_BIN) --headless --path . -s res://addons/gut/gut_cmdln.gd -gdir=res://tests -gexit
+
+check: lint validate-data test
+
+export-linux:
+	@echo "Export Linux : pas encore configure (voir Ordre de construction, etape 6)."
+	@exit 1
+
+export-windows:
+	@echo "Export Windows : pas encore configure (voir Ordre de construction, etape 6)."
+	@exit 1