What WILL break compatibility

Changes that REQUIRE a major version bump:

• Changing deterministic execution semantics or ABI.
• Removing or renaming public API modules: bijux_vex.core.types, bijux_vex.core.contracts.execution_contract, bijux_vex.core.runtime.vector_execution, bijux_vex.contracts.resources, bijux_vex.services.execution_engine, bijux_vex.api.v1.
• Changing public error types or their messages for deterministic paths.
• Changing OpenAPI v1 schema in a non-additive way.
• Altering provenance structure such that existing artifacts cannot be replayed/validated.

Changes that do NOT require a major bump (but still need tests/docs):

• Additive OpenAPI v1 fields with safe defaults.
• New internal modules or refactors that do not touch public surfaces.
• Performance improvements that preserve deterministic behavior and ND envelopes.
• Additional examples or docs that do not alter contracts.