fix(bot): return translated error when moving ticket to a full Discord category

[Akinator31]

This pull request improves error handling when moving channels to Discord categories that have reached their maximum capacity. It introduces a new error type to represent this situation and ensures that users receive a clear, localized message when the error occurs.

Error handling improvements:

• Added a new DiscordError::CategoryFull variant to represent the case when a Discord category is full, and updated the error mapping logic in move_thread/common.rs to detect this specific error from Discord API responses.
• Updated the error message logic so that when CategoryFull occurs, a specific error message is returned instead of a generic Discord API error.

Localization updates:

• Added user-friendly, localized error messages for the new discord.category_full error in both English and French dictionaries, ensuring users are informed about the reason for the failure and possible next steps.

Integration with move channel logic:

• Updated the channel moving functions to use the new error mapping, so attempts to move a channel to a full category will properly trigger the new error and message.