docs: add standard module documentation

Initial README following the project's module documentation structure:
Abstract paragraph, Badges as bold key:value list, Topology section
with auto-generated mermaid graph, Controls describing player input,
Demonstrates listing the Sporel features showcased, References at
the end.

Install pre-commit hook via Sporel --install-hooks=.; topology is
auto-managed by Sporel --lint --fix.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -0,0 +1,41 @@
+# lib-sporel.launcher
+
+Module-discovery and module-switch entry. Lists available modules from the configured modules-dir and launches the selected one via `engine.switch_module`. Typical entry point: `--module=lib-sporel.launcher` boots into a chooser screen rather than directly into a game.
+
+**Version:** 0.1.0  
+**Module-ID:** lib-sporel.launcher  
+**Requires:** lib-core.input v>=0.4.0  
+**Tags:** launcher, menu, system, navigation
+
+## Topology
+
+<!-- topology:start (auto-generated; do not edit) -->
+```mermaid
+graph LR
+  this["lib-sporel.launcher"]
+  lib_core_input["lib-core.input"]
+  this --> lib_core_input
+  engine["engine.*"]
+  this --> engine
+```
+<!-- topology:end -->
+
+## Controls
+
+- **Mouse-Left**: Click a module-button to launch it; click confirm/cancel in the quit-modal.
+- **Enter**: Confirm quit when the modal is open.
+- **Escape**: Open the quit-modal from the chooser; cancel the modal when open.
+
+## Demonstrates
+
+- `engine.module.list` discovery of installed modules from the modules-dir.
+- `engine.switch_module` runtime swap from the launcher to the selected module.
+- Simple text + rect rendering via `engine.render` for the chooser UI.
+- Input-action binding through `lib-core.input` (`ui_click`, `ui_back`, `ui_confirm`).
+- Modal-state FSM (chooser <-> quit-modal) factored into a sibling `fsm.lua` loaded via `engine.module.dir_of`.
+
+## References
+
+- meta/docs/architecture/module-lifecycle.md
+- meta/docs/architecture/host-app.md
+- meta/docs/superpowers/specs/2026-05-14-launcher-design.md