[vitormattos]

Issue #95 — post-PR #101 NT009 normative preview guards

Follow-up to merged PR #101, based on main at 2c5c84630eab28e0653c40c793f1bb2ba4fab553.

Source-backed changes

• Enforce Annex VI v1.04.01 adjustment-type enumerations (row 298) and conditional text descriptions for 99/199 (row 299).
• Reject vAjusteAplic > vTotDoc (row 301) with arbitrary-precision decimal-as-string comparison, avoiding floats and integer overflow.
• Limit national DF-e reference types to 1/2/3/9 and xTipoChaveDFe to type 9 (rows 305–306).
• Limit property adjustment codes to 01/02/03/04/99 and xTpAjusteBCLocImoveis to 99 (rows 401–402).
• Permit the independent exterior IBS/CBS base adjustment (row 336) without a spurious ISSQN adjustment mode.
• Add eleven focused valid/invalid regression cases and describe the boundaries in docs/NT009-CONTRACT-IMPLEMENTATION.md.

Compatibility and safety

• No modifications to DpsData, legacy XmlBuilder::buildDps(), DpsSchemaValidator, NfseClient::emit(), or the downstream Akaunting dependency.
• These new checks affect only the opt-in, non-emitting NT009 preview, not currently emitted legacy fiscal XML.
• No rule is inferred from advisory Annex VIII.

Validation

• Base/head compare: one commit, five scoped files; verified OpenPGP signature and matching DCO.
• Source checks: committed, checksum-pinned 450-row Annex I/VI contract matrix.
• GitHub Actions and PHPUnit are pending as of opening; the execution environment did not provide a local repository/dependency checkout. Do not claim passing tests until checks complete.

Explicitly unresolved — do not close issue #95

The government portal does not yet establish a deployed environment-specific NT009-compatible official XSD and activation date. The unresolved gIBSCBSAjuste hierarchy conflict (NT009 PDF versus Annex VI), independent taxpayer-classification/repercussion rules, complete version-specific emitting API and XSD/SEFIN acceptance remain blockers. The preview is not a certified production emitter. Do not promote it to NfseClient::emit() or update akaunting-nfse's Composer pin on this basis.

This PR fixes the demonstrable post-#101 gaps that can be resolved without inventing fiscal semantics; it does not claim 100% completion of #95.