Allow Keybind Exclusivity in Task Assignment

⚬ PROBLEM:
The YouTube extension currently allows users to assign the same keybind to multiple tasks simultaneously, which can potentially lead to conflicts and confusion among users.

⚬ SOLUTION:
Introduce a feature that enables keybind exclusivity when assigning tasks. When a user selects a keybind for a particular task, the extension should prompt a dialog for confirmation before removing that keybind from any other tasks to prevent conflicts.

⚬ ALTERNATIVES:
I thought in two options:

• A dialog prompt for confirmation before removing the keybind from other tasks.
• Automatic removal of the keybind from other tasks without a confirmation dialog.

⚬ RELEVANCE / SCOPE:
This feature enhancement would benefit all users who utilize shortcuts, as it enhances clarity and reduces potential conflicts in task assignment.

⚬ SIDE EFFECTS:
I don't think that implementing this feature introduce conflicts or adverse effects.

⚬ CONTEXT:
This behavior aligns with common practices observed in many sites and applications, where the same keybind is typically not allowed to be assigned to multiple functions simultaneously.

The issue names no files, tests, or entry points. Start by locating the keybind assignment flow and its task-selection UI, then resolve whether confirmation is required before removing duplicate bindings; done means a selected keybind cannot remain assigned to multiple tasks and the chosen behavior is covered by tests.