Release v0.2.1: unified proof stack and orbital observatory

[JROChub]

Summary

• combine the v0.2 network/migration line with constant, seeded-affine, sparse, and commitment-bound proof modes
• publish a normalized v0.2.1 crate manifest, verification guide, release notes, and claim boundaries
• preserve PHSPv1/PHSMv1/PHCPv1 byte-for-byte reproducibility across the MFENX PRNG migration
• replace mfenx.com with a Three.js orbital world clock and executable browser verification console
• strengthen CI to test all targets, all features, public examples, and the independent Python verifier

Verification

• cargo test --all-targets --locked
• cargo test --all-targets --features net --locked
• cargo clippy --all-targets --all-features -- -D warnings
• cargo package --allow-dirty
• cargo publish --dry-run --allow-dirty
• Rust + Python million-round artifact replay
• Playwright desktop/tablet/mobile screenshots and all four browser verification actions