## Why

Recordings from the RTLSDR-Airband CB scanner are stored as MP3 files on the Pi's filesystem (`/home/m/recordings/`), organized by channel and date. There's currently no way to browse or listen to them without SSH access. A web server with directory listing would make recordings browsable and playable from any device on the local network.

## What Changes

- Add an Nginx container to `docker-compose.yml` that serves the recordings directory with autoindex enabled
- Users browse directories and click MP3 files to play them natively in the browser

## Capabilities

### New Capabilities
- `recording-browser`: Nginx autoindex serving the recordings directory over HTTP, with browser-native MP3 playback

### Modified Capabilities

_(none)_

## Impact

- **Docker deployment**: New Nginx service added to `docker-compose.yml`, sharing the `/home/m/recordings` volume (read-only)
- **Pi resources**: Negligible — Nginx Alpine uses ~2MB RAM
- **Network**: Exposes HTTP port on the Pi's local network