CoinbaseAccount::Processor uses the compact class form, so its lexical
nesting is only [CoinbaseAccount::Processor]. The bare `HoldingsProcessor`
reference in process_holdings resolved against that nesting and raised
`uninitialized constant CoinbaseAccount::Processor::HoldingsProcessor`
instead of finding CoinbaseAccount::HoldingsProcessor.
The error was swallowed by the rescue around process_holdings, so every
Coinbase sync logged the failure and skipped the holdings step while the
balance path still completed. Holdings and value never refreshed.
Qualify the reference to CoinbaseAccount::HoldingsProcessor so it resolves
absolutely, matching every sibling processor (Binance, Kraken, Snaptrade,
Questrade, Indexa).
Fixes#2412
Co-authored-by: agentloop <agentloop@localhost>
