v1.2.1

### Audio
- Add WASAPI loopback capture for Windows — auto-captures desktop audio (what's playing through speakers) without requiring Stereo Mix
- WASAPI backend uses `windows` crate COM APIs: `IMMDeviceEnumerator` → `IAudioClient` (loopback) → `IAudioCaptureClient`
- Same fallback pattern as Linux: try WASAPI loopback first, fall back to cpal input devices
- Supports float32, int16, and int24 formats with stereo→mono downmix
- Device friendly name shown in status bar (e.g. "Speakers (Realtek Audio)")

### Bug Fixes
- Fix webcam "Failed to fulfill requested format" on Windows: cameras that only support raw formats (YUYV/NV12) now work via automatic fallback from MJPEG to any supported format

### CI
- Upload debug build artifacts on PRs for all platforms

## Downloads

| Platform | File | Notes |
|----------|------|-------|
| **macOS** | `.dmg` | Universal binary (Apple Silicon + Intel) |
| **Linux x86_64** | `.tar.gz` | glibc 2.35+ (Ubuntu 22.04+, Debian 12+) |
| **Windows x64** | `.zip` | Windows 10+ |

## Getting started

**macOS**: Open the DMG, drag Phosphor.app to Applications (or run directly). Signed and notarized.

**Linux / Windows**: Extract, run `phosphor` from the extracted directory. The `assets/` folder must be next to the binary.

## Requirements

- **GPU**: Vulkan (Linux/Windows) or Metal (macOS)
- **Audio**: Built-in mic or line-in for audio-reactive visuals
- **NDI®** (optional): [NDI® SDK runtime](https://ndi.video) for network video output
- **Video playback** (optional): `ffmpeg` on PATH for media layers

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