Recognize durable history shape rejection evidence

[rmcdaniel]

Summary

Allow descriptive durable-history shape rejection evidence in the replay corpus
used by the cancellation scope work.
An authored Activity must not reuse a position already reserved by a recorded
scope. The new Native fixture uses workflow_history_shape_mismatch and the
official HistoryEventShapeMismatchException outcome.

Also recognize search_attribute_type_identity_mismatch, already supported by
Native's validator and checked-in typed Search Attribute replay fixture. The
shared schema previously rejected that existing valid evidence.

Verification

All 67 retained shared-contract tests pass in an ephemeral container with
Python 3.12.3, jsonschema 4.23.0 and PyYAML 6.0.2. Schema self-validation,
representative new rejection evidence, and existing unknown-type/extra-field
rejection checks pass. Repository CI is required before merge.

This changes evidence vocabulary only. It advertises no cancellation capability,
changes no Worker protocol default, and does not complete or close shared #136.

[rmcdaniel]

Maintainer review at 657e536: two additive evidence failure names, strict rejection shape and unknown-type refusal preserved. The supported Native search-attribute outcome and new cancellation scope reserved-position fixture both have descriptive vocabulary. No worker capability, protocol default, production behavior or approval boundary changes. Local retained-contract suite: 67 tests pass. Required Repository checks run 37091739153 passes. Safe to merge this schema prerequisite. Shared #136 remains open.