fix: apply CEI ordering to license purchases

[sirakinb]

Summary

• persist the license record and listing sale/status updates before payment transfers in purchase_license
• keep creator and platform-fee transfers after storage effects are committed
• expand purchase coverage to assert sale count and buyer/creator balances

Tests

• cargo fmt -p pulsar-creative-marketplace --check
• cargo +1.91.1 test -p pulsar-creative-marketplace

Refs #555

[sirakinb]

Rebased this branch onto current main and kept the license/listing effects before payment transfers.

Verification after rebase:

• cargo +1.91.1 fmt -p pulsar-creative-marketplace --check
• git diff --check
• cargo +1.91.1 test -p pulsar-creative-marketplace (13 passed)