WA-NEW-006: Fix Payment#complete? to treat zero authorization as incomplete

[jhill]

Goal: Make complete? return false when payment.credit_card.amount is zero (or otherwise non-authorizing) to satisfy expectations and avoid placing invalid orders.

Symptoms: Workarea::Checkout::Steps::PaymentTest#test_complete? fails because amount = 0 still yields complete? == true.

Verify: bundle exec ruby -Icore/test core/test/models/workarea/checkout/steps/payment_test.rb

Branch: wa-new-006-payment-complete-zero-amount
PR target: next

[jhill]

Completed on branch (commit 3eae95f). Summary: fixed Pricing::Request#save_order persistence under Mongoid 7 by switching BSON-producing to JSON-safe (and string-key reverse_merge), and added a credit-card authorizable amount guard so /bin/zsh authorizations don’t mark Payment step complete. Verified with payment/checkout/pricing tests all green.

[jhill]

Completed on branch wa-new-006-payment-complete-zero-amount (commit 3eae95f).

Summary:

• Fixed Pricing::Request#save_order persistence under Mongoid 7 by switching BSON-producing as_document to JSON-safe as_json (and using string keys in reverse_merge to avoid symbol/string duplication).
• Added a credit-card authorizable amount guard so $0 authorizations don’t mark Payment step complete.

Verification: payment/checkout/pricing tests all green (per task report).

[kitcommerce]

Heads up: this issue is still OPEN but has label status:done. If the work is truly complete/merged, we should close the issue (or swap the label back to status:ready/in-progress). Let me know if you'd like me to propose the exact cleanup (close vs relabel) once we confirm the related commit/PR.

[kitcommerce]

FYI: this issue currently has both status:done and status:ready-for-review. Per lifecycle semantics, it should only have one status label. Tracking cleanup in #639.