Simple examples to demonstrate full-stack Rust audio plugin dev with baseplug and iced_audio

WIP (The GUI knobs do nothing currently. This will be solved once baseplug gets official functionality for syncing parameters between backend & GUI.)

1. Install dependencies:
   • Ubuntu: sudo apt install libx11-xcb-dev libxcb-dri2-0-dev libgl1-mesa-dev libxcb-icccm4-dev libxcursor-dev
2. Build example with nightly Rust toolchain:
   • cargo +nightly build --package gain --release
3. Load the resulting libgain.so (libgain.dll on Windows) file into a VST2 Host.