Checkpoint 1: implement native subsystems and begin the gameplay manual

docs/manual/index.md

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+# Faset Engine Manual
+
+Faset is a C++ engine for desktop 2D and 3D games on Linux and Windows.
+This manual focuses on writing gameplay: small working examples, the functions they use,
+and how those functions interact with scenes, physics, and the editor.
+
+!!! warning "Development status"
+    MVP implementation is in progress. A planned feature is not a working feature.
+    Individual guides state their prerequisites and validation status. The current
+    foundation can be built and tested; a complete editor and game export are not yet available.
+
+Start with [how C++ gameplay works](scripting/index.md), then read
+[frame and physics updates](scripting/lifecycle.md). See
+[Build from source](getting-started/build.md) for the toolchain and build commands.
+
+The engine, editor, built-in diagnostics, and API identifiers use English.
+Your game content and project text can use other languages.
+
+## Learning path
+
+The manual grows alongside tested engine capabilities, in this order:
+
+1. Build and run an example game.
+2. Create a C++ behavior and expose a property in the Inspector.
+3. Handle input and move a character.
+4. Use physics, collision events, and deferred object creation.
+5. Work with scene templates, assets, and references.
+6. Import from Blender and export a standalone game.
+
+Lua is planned after the C++ foundation. It is not a current scripting option.
+
+## Preview this manual
+
+From the repository root, create a Python virtual environment and install the pinned documentation tools:
+
+```sh
+python3 -m venv .cache/docs-venv
+.cache/docs-venv/bin/python -m pip install -r docs/requirements.txt
+.cache/docs-venv/bin/python -m mkdocs serve
+```
+
+On Windows, use `py -m venv .cache/docs-venv` and
+`.cache/docs-venv/Scripts/python.exe` in place of the Unix interpreter path.
+The manual also remains readable directly as Markdown in the repository.