feat: add local activation for lorebook

[bangonicdd2]

PR Checklist

• Have you checked if it works normally in all models? Ignore this if it doesn't use models.
• Have you checked if it works normally in all web, local, and node hosted versions? If it doesn't, have you blocked it in those versions?
• Have you added type definitions?

Description

This PR adds a toggle to enable lore books specifically for the current chat session. This feature is expected to be particularly useful for simulator-style chatbots as it allows users to select and activate specific lore books for each chat from a pre-configured set. Please note that this is still an early implementation, and I'm open to any feedback or suggestions.

[bangonicdd2]

After some consideration, the current fake-sync concept might confuse users who want to constantly edit their lore books.

I'll refine this and work on implementing a proper global/local lore book sync feature.