Add a compatibility check between `docs/api-reference.md`'s documented error codes and both contracts' actual error enums

[fejilaup-cloud]

Labels: documentation, bug
Priority: Medium
Estimated Time: 1.5 hours

Description:
Given ip_registry's ContractError currently has only 5 variants (per #92) while atomic_swap's has roughly 60, and both are surfaced through the API server once handlers are wired (#49), confirm docs/api-reference.md accurately lists every error code a client can actually receive from each contract, not a stale or partial subset.

Tasks:

• Generate the documented error-code list directly from each contract's error enum rather than hand-maintaining it
• Add a CI check that fails if docs/api-reference.md's error table and the contracts' enums diverge
• Cross-link this with Implement swap_count view function #58's OpenAPI regeneration check

[Peculiarr7]

Hi! I’m a full-stack developer with a strong blockchain background, and I’m confident I can resolve this issue quickly and effectively. I’ll deliver a clean, reliable solution with immediate attention to detail, ensuring it’s completed as soon as possible. Please assign it to me—I’m ready to get started right away.