Replaces `write_text_file` and `write_image_file` with backend commands
`save_text_file_dialog` and `save_image_file_dialog`. Instead of allowing
the frontend to pass an arbitrary absolute path, the Tauri backend now invokes
the OS save dialog directly, eliminating the risk of arbitrary file write
if the frontend is compromised.
Co-authored-by: Horizontal42 <75383519+Horizontal42@users.noreply.github.com>
Signed by a new key (public half embedded in tauri.conf.json, private
half + password live in GitHub secrets). CI now signs release artifacts
and publishes latest.json; the app checks on boot and prompts to
install and restart.
Write plain text, get live results per line. English + Russian, units,
live currency rates with crypto, percents, dates and timezones, bitwise
ops, variables and sheet totals. Tauri 2 + TypeScript engine +
CodeMirror 6; daily backups and a deleted-sheets bin.
Inspired by Numi for macOS (numi.app); built from scratch for Windows.
