PSYCHEDELIC SCREENSAVER - desktop program
Same Rust engine as the website. Mouse move or Esc exits.

LINUX
  chmod +x screensaver-desktop
  ./screensaver-desktop /s --shapes "star, hexagon, heart" --mode tunnel
  As an xscreensaver hack: copy it somewhere on PATH and add a line to ~/.xscreensaver:
    psychedelic-screensaver  /s

WINDOWS
  1. Install Rust from https://rustup.rs/
  2. cargo build --release -p screensaver-desktop
  3. Rename target/release/screensaver-desktop.exe to PsychedelicScreensaver.scr
  4. Right-click the .scr -> Install. (It understands /s run, /c and /p show help.)

MAC
  cargo run --release -p screensaver-desktop -- /s
  (macOS .saver bundles need Xcode signing; the program itself runs fullscreen as-is.)

FLAGS
  /s  run as the screensaver (a renamed .scr answers /s /c /p on Windows)
  --shapes "star, ring, banana, 7"   any words/numbers become shapes
  --mode kaleidoscope|mandala|fractal|spiral|tunnel|flower|orbitals|lattice|flow|weave
  --speed 0-3                        pattern speed
  --symmetry 2-24                    mirror count
  --camspeed 0-3                     camera speed
  --flight orbit|through|spiral|drift
  --density low|default|high|0-100   how much geometry fills the scene
  --evolve 0-1                       self-evolution amount
  --time SECONDS --warm N --width N --height N --bench N   headless tuning
  --snapshot out.ppm                 render one frame without a window

SOURCE: the website project itself (core/ is the shared engine, web/ is the
WebAssembly site, desktop/ is this program). cargo test runs the engine tests.