Add automated desktop releases

[Laxyny]

Summary

• Add a GitHub Actions release workflow for Tauri desktop bundles on Windows, Linux, macOS arm64, and macOS x64.
• Add a release preparation script to keep Rust, Tauri, npm, and Python versions synchronized.
• Document the release process, expected artifacts, GitHub settings, and future updater path.

Verification

• node scripts/prepare-release.mjs 0.1.0 --dry-run
• cargo test -p inspectra-core
• npm --prefix inspectra-gui ci
• npm --prefix inspectra-gui run build

Local Windows build produced:

• target/release/bundle/msi/Inspectra_0.1.0_x64_en-US.msi
• target/release/bundle/nsis/Inspectra_0.1.0_x64-setup.exe