VV: Create Element Array from Feature Array fully V&V'ed

[imikejackson]

Summary

Full V&V of CopyFeatureArrayToElementArrayFilter per the v2 MTR V&V policy (Class 1 Analytical oracle + Class 4 Invariant companions), followed by a five-review hardening pass (adversarial, senior-engineer, CPU-perf, memory-perf, out-of-core). V&V report/deviations are archived to OneDrive per program decision.

Correctness

• Class 1 analytical oracle (hand-derived indirection-lookup constants on a 4x3x1 / 4-feature fixture across float32/1-comp, int32/3-comp, and bool arrays) encoded as inline test assertions; SIMPLNX matched exactly.
• A/B vs DREAM3D 6.5.171: numeric output bit-identical on valid input (re-verified after the kernel rewrite). 3 documented deviations, all naming/validation semantics: D1 output naming for converted pipelines; D2 over-provisioned feature array accepted in NX (legacy error -5555); D3 legacy bug — silent out-of-bounds garbage for negative feature ids (NX errors -5355).

Bug fixes

• Selecting a NeighborList/StringArray threw an uncaught std::bad_cast from preflight — parameter now constrained to ArrayType::DataArray (pinned by test).
• A / in the created-array suffix threw an uncaught std::invalid_argument — now a clean preflight error (-3021).
• Zero-tuple FeatureIds dereferenced end() (UB) in the shared ValidateFeatureIdsToFeatureAttributeMatrixIndexing — empty-store guard added.

Performance

• Raw-pointer fast path in the copy kernel when all three stores are concrete in-core DataStore<T> (removes ~3 virtual calls per component-element); OOC/other store types keep the serial virtual path (requireArraysInMemory added).
• FeatureIds min/max validation hoisted out of the per-selected-array loop (was one full array scan per selected array).

Tests

• 21 ctest entries (was 17), 13 of 14 enumerated code paths exercised (cancel path excluded). New negative tests: non-DataArray selection, / suffix, name collision (-266), zero-tuple FeatureIds, negative id (-5355), id-out-of-range (-5351), over-provisioned pin (D2). The TEMPLATE_LIST test previously compared uninitialized feature data (could not detect indexing bugs) — now uses distinct per-feature values. SIMPL backcompat test now asserts the converted multi-path value.

Docs

• Xmdf→Xdmf typo, suffix/multi-array naming semantics, validation error codes, memory note, example pipelines.

Test Plan

• All 21 filter tests pass on in-core build
• All 21 filter tests pass on out-of-core build configuration
• Full SimplnxCore suite green in-core (one pre-existing unrelated failure: EMsoftSO3SamplerFilter missing SIMPL fixture in SimplnxReview)
• A/B comparison vs 6.5.171 re-run post-rewrite: bit-identical