Release 2.7.0: plaintext comparison for encrypted fields, Flatten with InferRules, FloatCast finite, PHPStan level 6

[yuriizee]

Fixed

• equals(), diff(), DataObjectCast::compare() and DataCollectionCast::compare() compare EncryptedCast fields by their decrypted value. Equal objects no longer differ because each toArray() draws a new nonce, and saving an unchanged model no longer rewrites the encrypted column. diff() still reports ciphertexts, never plaintext (S1-09).
• A required #[Flatten] property under #[InferRules] rejected valid flat input ("address is required"); the nested rules now apply to the parent's own keys. Nullable/defaulted #[Flatten] keeps the prefixed rules (S3-F16).

Added (opt-in)

• FloatCast(finite: true) rejects INF / NAN (e.g. 1e400 in JSON) at hydration (S3-F11).

Changed

• PHPStan level 6: array, iterable and generic types documented across src; fixtures exempt from missingType.*.
• Docs: XML entity handling (DTD entities are never expanded) (S3-F17), comparison of encrypted and hidden fields.

Performance

• Hydration/serialization benchmarks, interleaved before/after: medians within ±2.2% (noise), memory identical.
• equals() 615 → 603 ns; diff() +1–4% (one static property read). The plaintext pass runs only when the compared objects actually encrypted something.

Verification

• Docker: 887 tests, 100% line coverage (2173/2173); PHPStan level 6 clean; Infection covered MSI 86%.

Backward compatible with 2.6.x.