Filen CLI: allar útgáfur og eldri útgáfur

This release contains a migration from the Node runtime to Bun, which brings internal improvements. See #368 for technical details.
There should be no user-facing changes except for a startup performance increase of (very) roughly 20%.
See the README for installation instructions and more.

This release contains extensive internal architectural changes and testing, enabling more stability and future development velocity (see #357).
User-facing changes:
- in-app documentation (the help command) is much more complete
- the readme documentation is replaced by a HTML rendering of the in-app documentation (available at docs.cli.filen.io and attached to releases); the long-form documentation at docs.filen.io remains
- all commands are now also available in interactive mode
- many more fixes and improvements
See the README for installation instructions and more.

Features:
- new filen export-notes command
See the README for detailed information.

Fixes:
- fixed where Docker image crashes on startup because of missing libsecret-1.so.0 dependency
See the README for detailed information.

Features:
- binaries are now available for all target platforms (Windows/Linux/macOS, arm64/x64)
- credentials are now saved more securely using an encryption key stored in the system keychain
See the README for detailed information.

Features:
- new filen export-api-key command to export your Filen account API key (which is used to authenticate the upcoming Filen Rclone tool)
See the README for detailed information.

Features:
- installing the CLI by executing an install script via curl -sL https://filen.io/cli.sh | bash (which is a redirect to https://raw.githubusercontent.com/FilenCloudDienste/filen-cli/refs/heads/main/install.sh)
- installing the CLI from the NPM package @filen/cli via npm i -g @filen/cli and invoking it as filen
This release contains all latest improvements of Filen packages.
See the README for detailed information.