Release: Windows + Linux builds (extend pantry-orchestrated DMG flow)

Context

We just shipped the macOS .dmg to GitHub Releases via the pantry-orchestrated build (commit 1c89320). The build is wired through scripts/package.ts using @craft-native/craft.

What's missing

Same release flow needs to also produce:

• Windows — .exe installer (or .msi)
• Linux — .AppImage and/or .deb

Why

Right now non-mac users have nothing to download from the Releases page. The whole point of the pantry-orchestrated flow is that it can target multiple platforms — we just stopped at one.

Acceptance

• gh release view <tag> shows mac + windows + linux artifacts attached
• One CI workflow handles all three (matrix build) without per-platform forks
• Artifact sizes documented in the release notes