Added Live Streaming via ALSA Loopback Device

[douxxtech]

This PR implements live audio streaming functionality for BotWave, allowing applications like raspotify and snapcast to broadcast audio to FM radio in real-time through an ALSA loopback device. This PR is related to #24.

Caution

Do not merge yet ! We first need the ToDo list completed.

What's New

Core Features

• ALSA Loopback Support: BotWave now appears as an ALSA audio output card named "BotWave"
• Live Streaming Command: New live command for local and server modes
• Real-time Broadcasting: Applications can output audio directly to BotWave for immediate FM transmission
• HTTP PCM Streaming: Protocol support for streaming raw PCM audio data over HTTP

Protocol Changes (v2.0.1)

• Added STREAM_TOKEN command for initiating live streams
• Implemented HTTP PCM streaming endpoint (/stream/{token})
• Enhanced error handling for unknown commands
• Removed RESTART command since it wasn't really used

ToDo

Before merging, we need confirmation that:

• ALSA loopback card is properly created and detected
• Audio applications can successfully output to the BotWave device (tested with aplay, vlc)
• Live streaming works reliably without audio glitches (fixes in backend solved that)
• Client-Server transmission is stable and has fallbacks
• Installation/uninstallation scripts work correctly
• Installer/updater links are updated
• The feature works with target applications (raspotify, snapcast)
• Documentation and built-in help are updated
• Closes FEATURE -> Live Streaming ALSA device? #24