[ greenart7c3/Amber ] Refactor: Move logging to a separate database

This commit moves all logging functionality into a new, separate `LogDatabase`.

Key changes include:

* Creating a `LogDatabase` and `LogDao` to handle all log entries.

* Removing the `LogEntity` and related queries from the main `AppDatabase` and `ApplicationDao`.

* Introducing a new `MIGRATION_14_15` to drop the old `amber_log` table from `AppDatabase`.

* Updating all call sites to use `Amber.instance.getLogDatabase(npub).logDao()` instead of the old `applicationDao` for logging operations.

https://github.com/greenart7c3/Amber/commit/86e2af359773cc9f6db203bd03e4d22139a79203