feat: select cTribNac from official catalog

[vitormattos]

Summary

Implements the next slice of #337.

• replaces the free-text cTribNac field with the existing searchable select UI;
• loads the complete official national-service catalog offline;
• displays code - official description;
• preserves existing persisted codes, including a visible legacy fallback if a saved code is not present in the current catalog;
• keeps LC 116 and cTribNac independent: no automatic correlation is introduced;
• adds runtime-contract and feature coverage.

Dependency

Depends on LibreCodeCoop/nfse-php#93, which exposes OfficialDomainCatalog::searchNationalServices().

The scoped runtime is temporarily pinned to that PR commit and must be repinned to the merge commit after #93 lands.

Related: #337