v1.2.1

SimpleSpread v1.2.1

Changes since v1.2.0

A native macOS spreadsheet: XLSX native format, CSV import/export,
and a Google-Sheets-level formula engine.

Note: This build is arm64 (Apple Silicon) only.
If Gatekeeper blocks the app, right-click → Open on first launch.

Commit Summary

• Add Open Recent (sandbox-safe) and a README screenshot (fb03bff)
• appcast: publish v1.2.0; fix updater signing to use --ed-key-file (3dd8240)