[Feature]: Custom Action, macros, sending shortcuts

### Pre-flight checklist

- [x] I searched existing issues and the [Roadmap](https://github.com/AprilNEA/OpenLogi#roadmap), and this isn't already tracked.

### Problem / motivation

we currently cannot do that

### Proposed solution

Implement a 'generic' action that users can define, first in config, later in UI but it would require some UI redesign / refactor to include a sidebar IMO.

The generic action could be a shortcut or a Keycode script like QMK macros for example

https://docs.qmk.fm/feature_macros

### Alternatives considered

_No response_

### Related area(s)

- [x] GUI
- [x] CLI
- [ ] Button actions / remapping
- [ ] DPI
- [ ] SmartShift
- [ ] Per-application profiles
- [x] Configuration (TOML)
- [ ] Auto-update
- [x] Other

### Additional context

Core, GUI, macros, Mappings

Start by reading the Core, GUI, Mappings, and TOML configuration areas named in the issue, along with the QMK macros reference. Clarify the action model and scope across configuration, GUI, and CLI before implementation; done should include a defined generic action supporting shortcuts or keycode scripts.

Written by the indexing model from the issue text.