feat: add microui-based GUI with transport controls and progress bar

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

docs/usage.md

@@ -1741,3 +1741,26 @@ clicked increments that integer, could be implemented as such:</p>
   </body>
 </html>
 
+# Usage
+
+## Overview
+
+The Jack Looper application provides a simple audio loop player using JACK.
+
+## Getting Started
+
+1. Ensure JACK is running
+2. Run `./jack-looper`
+3. Use the TUI interface to control playback
+
+## Controls
+
+- Space: Play/Stop
+- Up/Down: Change BPM
+- Left/Right: Change loop length
+- R: Reset beat position
+- Q: Quit
+
+## Building
+
+Run `make` to build all targets.