[SPIKE] Determine migration strategy from legacy builds to custom phrase/category builds

The previously released app didn't support modifying or removing preset categories and phrases like the new build is going to. We need to evaluate how we're going to migrate users, and whatever their states are, from the old build to the new build where this is possible.

We need to avoid creating duplicate categories/phrases for these users, while also not losing their custom state. It's possible the approach here is to detect a legacy build and just not touch presets at all.

We won't get into this until the Phrase/Category abstractions are complete.

Some considerations:

• If someone changes/removes the resource names for a phrase and the old one is already in the database, what happens? How can we handle this gracefully

Start by reviewing the Phrase and Category abstractions referenced in the issue, then inspect how legacy and new builds represent preset and custom state in the database. Done means documenting an agreed migration strategy that avoids duplicate phrases or categories and preserves supported custom changes.