Feature Request: Sync Brave Shields Filters Across Devices

Description: Currently, Brave Sync does not include custom filters set in the Shields section of settings or other user-added filters. This results in inconsistent privacy settings across synced devices, requiring manual configuration on each device. Adding filter synchronization would ensure a seamless and consistent user experience.

Proposed Solution: Extend Brave Sync to include Shields custom filters and settings. When a user adds or modifies filters on one device, these changes should sync to all devices in the Sync Chain, similar to bookmarks or passwords.

Use Case:

• Users with multiple devices (e.g., PC, laptop, phone) want consistent Shields settings without manually replicating filters.

• Ensures privacy preferences, like custom content blocking rules, are uniformly applied across devices.

Implementation Considerations:

• Add Shields filter data to the syncable data types in Brave Sync v2.

• Ensure client-side encryption (as used for other sync data) is applied to protect filter settings.

• Update the Sync settings UI to include a toggle for enabling/disabling filter syncing.

• Handle potential conflicts (e.g., device-specific filters) by merging or prioritizing based on user-defined rules.