refactor(deck-picker): AUTOMATIC_SYNC_MINIMAL_INTERVAL

[david-allison]

There was a lint warning due to .., so I cleaned up the code a little while I was here.

• Use the Kotlin 'Duration'

Assisted-by: Claude Opus 4.7 - self-review

Checklist

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
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