Camera fixes, documentation polish, crate packaging cleanup.
Fixed
- Camera init restored to proven (0,0,5) at origin; all AABB/scene-center heuristics removed
- Orbit mode always targets origin; WASD no longer shifts the orbit center
- Crate package excludes large scene files and binary assets
Changed
- Demo image switched from GIF (9.3 MB) to animated WebP (4.4 MB)
- README rewritten: CPU-first intro, features table, hardware benchmarks
- --cpu flag hidden behind metal feature gate
- No-args prints help instead of running demo
- AppResult consolidated to single crate-level definition
Full changelog: https://github.com/buildoak/tortuise/blob/main/CHANGELOG.md