Adds the extensibility design that hoists the bulk-edit operation
definition (today smeared across serialisers.py, views.py, bulk_edit.py
and keyed three different ways) behind a BulkEditOperation registry +
PermissionRequirements value object, with per-operation OpenAPI examples.
Contract-preserving refactor; both docs reviewed across multiple passes
(permission matrix verified, both view call sites accounted for).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Replace the search-error-shapes stub with a full design spec and a TDD
implementation plan for friendlier advanced-search error messages.
Empirically validated against a live Tantivy index: three error families
(UnknownFieldError, InvalidFieldValueError, MalformedQueryError),
proactive numeric validation plus a parse_query backstop, comparison
operators confirmed working, and a parse-based field drift guard.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>