Adds a per-field sorted column store (Lucene doc values + roaring bitmap
architecture) that replaces the MetadataIndex sparse index internals for
both filtering and sorting. One system for all field types with exact
precision — no bucketing, no per-entity storage reads.
Column store: binary .cidx segment format, in-memory tail buffers,
LSM-style compaction, k-way merge sort, multi-value support (__words__).
All queries (filter, range, sort, filtered sort) route through the column
store when data is available, falling back to sparse index otherwise.
Key unlocks:
- find({ orderBy: 'createdAt' }) works WITHOUT a filter (previously threw)
- find({ orderBy: 'metadata.price' }) works for custom numeric fields
- Exact timestamp precision (no 1-minute bucketing)
- O(K log S) sort independent of total entity count
New files: src/indexes/columnStore/ (types, format, tail buffer, cursor,
manifest, coordinator — ~700 lines). 101 new unit tests covering binary
format round-trips, CRC validation, sort, filter, range, deletion,
multi-segment merge, persistence, and multi-value (words) fields.
Deleted: metadataIndex-automatic-bucketing.test.ts (bucketing behavior
eliminated by exact-precision column store). Sparse index write path
removed from addToIndex/removeFromIndex. Sparse index legacy code still
present as dead code pending cleanup in next commit.
Muse reported that find({ orderBy: 'createdAt' }) silently returned the
wrong order: getFieldValueForEntity read noun.metadata[field] for
timestamp fields, but getNoun() destructures standard fields to the top
level, so the read always returned undefined and the sort collapsed to
insertion order.
The fix introduces a single source of truth for reading fields off an
entity. STANDARD_ENTITY_FIELDS + resolveEntityField() in coreTypes.ts
encode the "standard fields top-level, custom fields nested" contract
in one place. getFieldValueForEntity now uses the helper and routes
through a named BUCKETED_INDEX_FIELDS set instead of a hardcoded
timestamp if-chain — filtered sort on createdAt/updatedAt now works.
Unfiltered orderBy is explicitly rejected with a clear error pointing
callers at the right pattern. A scalable, unfiltered-sort-capable
time-ordered segment index is tracked as a separate follow-up.
