Get Credits Activity

Where the balance came from — every credit deposit as a human-readable line (Gleb, T-17 thread: "юзер совсем не понимает, откуда у него на балансе бабки").

Reads the wallet ledger's add rows (bil_wallet_slot_log): trials, referral bonuses, coupons, and real-money top-ups (price_per_unit > 0 on the slot). $0 marker rows (deferred/explore trials) and internal hold releases are noise, not deposits — excluded.