feat: make Ropy more custumizable

[fu050409]

Motivation

For now, Ropy supports some configuration:

However, for me, some keyboard shortcuts are just unacceptable—like using the D key to delete an item... It’s just too easy for me to hit that key by accident. I think it would be better if users could customize them:

Also, it's better if we can customize themes instead of just few presets.

Proposed Solution

Alternatives Considered

No response

Acceptance Criteria

• Convert shortcut descriptions into a custumizable settings page
• Allow user-defined themes placed at path like ~/.config/ropy/themes/..
• Allow configurations based on a config file like ~/.config/ropy/config.toml

Scope

gui