EventEntity
data class EventEntity(val id: Long, val rawHex: String, val maxId: Long, val blockHeight: Long? = null, val timestamp: Long? = null, val cachedAt: Long = System.currentTimeMillis())
Room entity for caching raw ledger events.
Purpose: Cache raw hex events from indexer locally so we can:
Replay events without re-syncing
Support offline mode
Reduce network traffic