Summary

Implements the Schema Migration System requested in issue #519.

• MigrationError — sealed ADT with 5 cases (FieldNotFound, TypeMismatch, TransformFailed, CaseNotFound, DecodeFailed); every error carries the DynamicOptic path for precise diagnostics
• MigrationAction — pure-data sealed ADT with 14 action types. No functions, no closures — fully serializable, storable in a registry. Every action carries its own structural reverse.
• DynamicMigration — applies an ordered Vector[MigrationAction] to a DynamicValue via a recursive path interpreter. Satisfies identity, associativity, and structural-reverse laws.
• Migration[A, B] — typed wrapper: encodes A → DynamicValue, runs DynamicMigration, decodes DynamicValue → B. Exposes reverse and andThen.
• MigrationBuilder[A, B] — immutable fluent DSL, cross-compiled Scala 2.13 + Scala 3.

Test results

38 tests passing on Scala 3.7.4 and Scala 2.13.16, JVM.

Closes #519

/claim #519

Contact: adam@onetechnologies.com