Lepton: äldre versioner att ladda ner

Substantial foundation upgrades
- Major components upgrades: Electron 42, Webpack 5, React 19, etc.
- Secure token storage https://github.com/hackjutsu/Lepton/issues/319
- More efficient memory management https://github.com/hackjutsu/Lepton/issues/465
- Bug fixes https://github.com/hackjutsu/Lepton/issues/539 https://github.com/hackjutsu/Lepton/issues/537 https://github.com/hackjutsu/Lepton/issues/532
New features
- All snippets/gists download + full content search https://github.com/hackjutsu/Lepton/issues/527 https://github.com/hackjutsu/Lepton/issues/254 https://github.com/hackjutsu/Lepton/issues/82 https://github.com/hackjutsu/Lepton/issues/208 https://github.com/hackjutsu/Lepton/issues/501
To enable full content download in .leptonrc.
- Built-in themes https://github.com/hackjutsu/Lepton/issues/541 https://github.com/hackjutsu/Lepton/issues/550
Supported values in .leptonrc's theme : light, dark, one-dark, atom-one-dark, github-light, github-dark, catppuccin-latte, catppuccin-mocha, solarized-light, solarized-dark, dracula, material-theme, ayu
Example: dracula
- Internationalization(i18n) support https://github.com/hackjutsu/Lepton/issues/459 https://github.com/hackjutsu/Lepton/issues/331 https://github.com/hackjutsu/Lepton/issues/411
- Option tag.colored to enable colored tags https://github.com/hackjutsu/Lepton/issues/484
- Option startAtLogin to start at system startup https://github.com/hackjutsu/Lepton/issues/551
- Option window.closeToTray and window.minimizeToTray to minimize to tray https://github.com/hackjutsu/Lepton/issues/553

For developers
- Update dependencies (e.g. Electron 8 -> 13)
- Auto-generate license and contributor lists when building the app
For users
- Open `.leptonrc` and the log file with OS default application when clicked on "About Page" (`Ctrl/Cmd + ,`) (#498)
- Highlighting for GraphQL (#494)
- Support login by GitHub token (#412)