DATE predicate evaluation

Simple DATE comparisons between columns/literals reuse DataFusion's ordinary comparison expressions over Arrow Date32. Previously the generic temporal guard selected Flink-generated Java evaluation for these predicates. The change follows Comet's comparison builders and Arroyo's direct DataFusion expression planning; there is no new Rust operator or memory pool.

Admission is limited to two DATE column/literal operands and the six ordinary comparison operators. Computed temporal expressions, mixed types, timestamps, TIME and null-safe distinctness keep their existing evaluation paths. NULLs preserve three-valued logic. DATE is compared as signed days, without a timezone conversion or calendar computation.

This removes the two registered Java evaluators from each TPC-H Q6/Q14/Q15 date-range filter. The separate SF1 release comparison still lost to stock: Q6 584.19/684.65 ms, Q14 685.04/868.95 ms and Q15 607.20/691.03 ms (stock/native medians). All three use identical files/resources, three warmups, seven alternating retained trials and complete job boundaries. These are local shared-host observations, not proof of complete-job acceleration. See the TPC-H trials and compatibility controls.

Batch EXPLAIN now exposes evaluator registration counts and generated-expression details, since an empty list of named JVM functions does not establish that a predicate has no Java bridge. Registration is not a runtime callback counter.