Prepare Reed 0.2.0 public release

[is2b007]

Summary

• adopt MPL-2.0 with notices and locked production dependency attributions
• prepare Reed 0.2.0 across desktop, Android, CLI, MCP, relay, and core packages
• add fail-closed macOS, Windows, and Android release-signing automation
• add checksum, GitHub Release, and itch.io/Butler publishing automation
• document signing, release notes, Android/DC1 support, and open-source readiness

Verified locally

• pnpm typecheck
• 31 Vitest files / 85 tests
• offline runtime test
• Android unit tests, lint, debug build, signed APK and signed AAB
• Electron macOS development package
• actionlint, shellcheck, gitleaks, and dependency-license audit
• signing guards reject incomplete Apple, Windows, and Android credentials

Release note

The release workflow is intentionally fail-closed. A public macOS/Windows binary release still requires the repository's Developer ID/notarization and Windows code-signing secrets; unsigned artifacts are not substituted.