feat(notifications): add file-based filtering rules

[ggyorfi]

Motivation

Adds support for filtering notifications via ~/.config/noctalia/notification-rules.json. Users can block, mute, or allow notifications based on app name, content patterns, urgency, etc.

Closes #1453

Type of Change

• New feature

Testing

• Tested on niri
• Tested on Hyprland
• Tested on sway
• Tested with different bar positions and density settings
• Tested at different interface scaling values
• Tested with multiple monitors (if applicable)

Manual testing performed:

• ✅ Notifications work without rules file (backward compat)
• ✅ Rules file auto-reloads on change
• ✅ Block action suppresses toast
• ✅ Mute action skips sound
• ✅ Both raw and transformed app names match

Screenshots / Videos

N/A (no UI changes)

Checklist

• Code follows project style guidelines
• Self-reviewed my code
• No new warnings or errors
• Documentation or comments updated (if relevant)

Additional Notes

• Example config: Assets/notification-rules-default.json
• Documentation: Added to README.md
• Future work: Settings UI, additional actions (notoast, snooze, modify)

[ItsLemmy]

I feel like this is too niche of a use case. Usually it's up to the application to offer proper control on notifications.

Also even tho external configuration files are cool, nowhere in Noctalia we rely on direct text editing for configuration.

This could probably be re-worked into a nice little plugin and I would be willing to accommodate an API change for the "evaluate" function to be run when a notification is processed, so that your plugin could work.