Release: cut v0.2.1 (binaries pipeline fixed in #641) + re-pin downstream quandledb

[hyperpolymath]

Tracking the tail of the v0.2.0 source-only regression.

Done

• fix(release): restore release binaries — immutable-release draft flow + portable BSD sed #641 (merged b8ba479) fixed .github/workflows/release.yml: draft→upload→publish (immutable-release compatible) + portable sed -i.bak (BSD/macOS). Compiler verified to build in release mode locally; --version/check work.

Remaining — owner action (a Claude-Code-web session can't push v* tags: git push → HTTP 403)

1. Cut the release from current main:

   git fetch origin main
   git tag -a v0.2.1 origin/main -m "v0.2.1 — restore prebuilt binaries"
   git push origin v0.2.1

   → the fixed workflow builds affinescript-{linux-x64,macos-x64,macos-arm64} + SHA256SUMS and publishes them.
2. Re-pin downstream quandledb: bump AFFINE_VER→0.2.1 and AFFINE_SHA256→(linux-x64 sha from the published SHA256SUMS) in .claude/hooks/session-start.sh; drop the v0.1.1 pin from quandledb PR fix(ci): eject rattlescript subtree, document TS exemptions (round 3) #60.

Acceptance

• Latest release has the three platform binaries + SHA256SUMS.
• curl -fsSL …/releases/download/v0.2.1/affinescript-linux-x64 is a runnable ELF; affinescript --version / check work.
• The binary checks a v0.2.0 source (e.g. quandledb quandle_gui.affine) with no parse error.