Fixes 0031. Every merge it made was provably one account — each split
pair shared an account_number — but the PREFIX generalises past that
evidence. Citibank Australia and Citibank India are different banks with
different accounts and currency, and `citi%` flattens them into one.
Older Citi India statements are queued to load, so this would have merged
them on arrival. Not Citi-specific: `hsbc%` and `%american express%`
carry the identical defect.
Currency alone cannot be the discriminator: Wise holds AUD, EUR and USD
accounts under one provider, so a blanket "non-AUD is a different bank"
rule would shatter it into three. Wise stays unmapped for exactly that
reason, now a documented property rather than an accident.
The country comes from the name when the name states it and from the
currency otherwise, with AUD as home taking no suffix — so nothing
renames: the backfill touched 0 rows.
'Citibank' + AUD -> 'Citibank' (unchanged)
'Citibank India' + INR -> 'Citibank India'
'Citibank N.A.' + INR -> 'Citibank India' (currency carries it)
'CITIBANK INDIA' + AUD -> 'Citibank India' (name beats a wrong currency)
'N.A.' is deliberately not read as a country marker: it means "National
Association", a US legal form printed on Citibank letterhead worldwide,
including India. Reading it as US is precisely the mistake this fixes.
The trigger now fires on UPDATE OF bank_name, currency, since the country
is partly derived from the currency.
