drift

Added

• custom themes — define your own themes in config.toml under [theme.<name>] using #RRGGBB hex colors; custom themes appear in drift list themes and showcase mode alongside built-ins; custom themes with the same name as a built-in override it
• dvd scene — the classic bouncing logo; a rounded box drifts around the terminal, changing palette color on each wall bounce and flashing bright on a corner hit; configurable via [scene.dvd]: speed, label
• scene transitions — a smooth fade-to-black between scene switches; duration controlled by engine.fade_seconds (default 0.3s per phase, 0 = instant cut); applies to both automatic cycling and showcase navigation
• config validation — Load() now rejects out-of-range values for all numeric config fields with a clear multi-line error listing every invalid field
• config validation — scene.waveform.layers must be 1–3; scene.particles.friction must be 0.0–1.0
• shell snippet tests — unit tests covering shellSnippet() for all supported shells and unsupported-shell error paths
• scene unit tests — test coverage for all 9 scenes: waveform, rain, constellation, life, maze, pipes, clock, starfield, particles

Fixed

• orrery scene — terminal resize no longer resets the RNG to the same seed used at init, preventing repetitive asteroid and UFO spawn patterns after resize events