Copycat v0.1.0 (test build)

Test build, not tried on many real recordings. The plugin window is a plain text window for now (the designed window is only in the mockup). One zip: installers for Windows (.exe), macOS (.pkg), Linux (Flatpak extensions and a plain .vst3), the PDF manual and INSTALL.txt. Everything works offline. SHA-256 sums are inside the zip.