New 'SMS balances' screen: every SMS client with its credit balance (the module's
own sms_balance service field), lowest first so the ones about to run dry sit on
top. Low = below sms.low_balance_threshold (dated setting, config over code);
'Low' is the default view = the upsell list. One click raises a top-up proforma
(reuses the module renewal-quote path); client name links to the Modules tab where
the balance is kept. Owner cockpit gains an 'SMS balance low' tile as the at-a-
glance alert. Read-only report, no audit. Test locks parse/flag/sort. typecheck +
web build clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Thomas Joise