Remove getModels suppression and enrich identity misses

[alexstandiford]

Summary

• remove the getModels() suppression path so datastore reread failures throw directly
• keep create() from degrading reread failures into follow-on null states
• enrich compound-identity misses with the table name and requested identity payload
• add unit coverage for the reread failure and missing-record identity paths

Why

The hidden obligation failure on Siren showed that swallowing datastore reread errors was the wrong behavior. If the reread fails, that should be the failure. And if an identity lookup misses, the exception should say which table and identity were involved.

Testing

• vendor/bin/phpunit tests/Unit/Traits/WithDatastoreHandlerMethodsTest.php