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>

README-EN.md

@@ -0,0 +1,44 @@
+# Les Aventuriers des mots (The Word Adventurers)
+
+An educational French-language game for 7-9 year olds (French grades CE1-CE2): an offline 2D adventure with an explorable map, a guide character, and grammar, spelling, and dictation exercises.
+
+Open source project, in development. Current status: technical skeleton (see `docs/specs/decisions.md` for scoping decisions and `docs/specs/cahier-des-charges.md` for the full specification, both in French — this is a French-curriculum product).
+
+## Tech stack
+
+- Godot 4.6 (typed GDScript)
+- Exercises and pedagogical content as JSON data, validated on load
+- Headless tests (GUT), GDScript lint/format (gdtoolkit)
+
+## Getting started
+
+```sh
+make setup   # installs Godot (pinned), GUT and gdtoolkit locally, nothing is committed
+make run     # runs the game
+```
+
+## Commands
+
+| Command | Effect |
+|---|---|
+| `make setup` | installs tooling (lint, tests, export templates) |
+| `make run` | runs the game |
+| `make lint` / `make format` | GDScript static analysis and formatting |
+| `make validate-data` | validates the JSON files in `data/` |
+| `make test` | headless tests |
+| `make check` | lint + validate-data + test, must pass before every commit |
+| `make export-linux` / `make export-windows` | exports into `build/` (from the export step onward) |
+
+## Structure
+
+- `autoload/`: global modules (game lifecycle, profiles, progress, exercises, saves, audio, settings)
+- `scenes/`: self-contained Godot scenes communicating via signals
+- `scripts/`: pure logic (correction, pedagogy) and data loading
+- `data/`: pedagogical content as JSON, validated against schemas
+- `assets/`: graphics and audio (placeholder at this stage, see `assets/CREDITS.md`)
+- `tests/`: headless tests (GUT)
+- `docs/specs/`: specification and scoping decisions (French)
+
+## License
+
+Code and content under the [GNU Affero General Public License v3](LICENSE).