Two issues that could cause ENS names to disappear:
1. refreshBalances: on ENS lookup error, addr.ensName was set to null,
wiping any previously resolved name. Now keeps the existing value
on error — only overwrites on successful lookup.
2. ens.js cache: failed lookups were cached as null for 12 hours,
preventing retries even after transient errors resolved. Now skips
caching on failure so subsequent lookups retry immediately.
Added debug logging to ENS reverse lookups in refreshBalances.
Deterministic colored dots derived from address bytes (16-color palette)
displayed before every address. ENS reverse resolution for transaction
counterparties with 12-hour localStorage cache.
