Promotion.promote() passed the same wallet UUID (WALLET_REWARD) as both
payer_wallet and payee_wallet, so every payout was routed out of and into
the same wallet type with no real company-owned pool. Add
WALLET_PROMOTIONS_TRANSIT as the dedicated payer_wallet, and rename
WALLET_RIAL/WALLET_REWARD to WALLET_RIAL_DEPOSIT/WALLET_USER_BILLBOARD_VISIT_INCOME
to match the naming used for the same wallet-service UUIDs in advertising/
settlement/ipg.
Also wires Recipient.get_wallet_category_uuid() (previously dead, and
falling back to an undefined setting) into the deposit call as payee_wallet,
so a Recipient can route its payout to its own wallet_uuid instead of every
payout hardcoding one constant.
Adds .env.example (none existed before) and docs/wallet_refactor.md
documenting the before/after and required .env changes per deploy target.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>