test: enforce official schema bundle integrity

[vitormattos]

Advances #48.

Summary

• extend the v1.01 schema manifest with the event XSDs merged in test: validate SEFIN event XML against official schema #77
• make the manifest executable in CI by recomputing Git blob identifiers locally
• document the explicit new-schema update procedure
• fail if an official reference XSD changes byte-for-byte without a deliberate manifest update

No runtime behavior changes. The official XSD files remain unmodified.

The commit is GPG verified and DCO-valid.