[Feature] Capture directly to clipboard or raw PNG output

[bitbalancer]

Please add options to capture a screenshot without opening the annotation editor, aligned with Flameshot’s CLI terminology:

rishot --clipboard
rishot monitor --clipboard

rishot --raw
rishot monitor --raw

Suggested behavior:

• --clipboard: copy the captured PNG directly to the clipboard;
• --raw: print the captured PNG to stdout;
• skip the annotation editor;
• write errors and status messages to stderr;
• return a nonzero exit code when cancelled or capture fails.

This would allow simple keybindings for direct clipboard capture and pipelines into other annotation tools such as Tensaku.

Thanks for sharing Rishot with the community and for considering this feature request.