Add option to clear query after running actions

[multiplex55]

Summary

• add a clear_query_after_run setting with documentation, defaults, and sample config updates
• expose the new toggle in the settings UI, propagate it through plugin/settings saves, and store it on the app
• clear the query after running actions when the option is enabled while keeping command-specific overrides intact

Testing

• cargo fmt
• cargo test (fails: missing system library alsa for alsa-sys build script)