Tuner Added + Safer Audio Connection Flow

New Tuner: open from the header when connected. The tuner listens to your input even when master output is muted, so you can tune silently on stage.

Audio connection enhancements: the engine now safely disconnects and reconnects when input/output devices change, and resets output volume to a safe level to prevent sudden loud peaks.

Low-latency improvements and a Live Mode reduce UI and effect overhead for tighter monitoring during performance.

Minor UX polish: disabled tuner button when not connected, clearer status messages, and improved device detection behavior.