refactor: codebase cleanup

[Robitx]

• making LSP diagnostics happy (fix deprecated methods and some type annotations)
• move helper methods into a helper.lua
• move whisper logic into a whisper.lua
• move image generation logic into imager.lua
• ad some useful debug logs
• move option deprecation logic into deprecator.lua
• move secret handling logic into vault.lua
• move os process handling logic into tasker.lua
• move provider handling logic into dispatcher.lua