feat: #3591388 add grants-hash render cache context for entity access

Peter Wolaninrequested to merge
issue/raft_entity_access-3591388:3591388-add-per-grants-render into 1.x

Replace the placeholder 'user' cache context with user.entity_access_grants:{type}:{op}, a calculated context keyed on a hash of the user's grants. Register the context service, invalidate a per-type records cache tag on rebuild(), and document both.

Add stateful- and dynamic-grants test sub-modules plus kernel and functional coverage.

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

Closes #3591388

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