…ide-int types + EET roundtrip identities)

Implements the plan's Phase-1 P0 fast wins from
docs/plans/2026-06-13-001-feat-clickhouse-coverage-backlog-30-ideas-plan.md.

New differential / ground-truth oracles (each default-on, gated by a --flag,
self-contained, soundness-checklist-compliant):
- #2  PrewhereEquivalence      WHERE == PREWHERE == optimize_move_to_prewhere=0 (multiset)
- #3  ReadInOrderToggle        optimize_read_in_order/aggregation_in_order on==off
- #4  CountOptimization        trivial/implicit/use_projections on==off + countIf cross-check
                               + GROUP-BY-key count arm (hardens #106573, #106125)
- #5  LazyMaterializationToggle query_plan_optimize_lazy_materialization on==off (positional)
- #12 ReplacingDedup           ReplacingMergeTree(ver) FINAL == argMax(val,ver) GROUP BY key
- sqlancer#19 QuantileConsistency      quantileExact==medianExact, monotone-in-level, Low<=Exact<=High
- sqlancer#20 UniqExactness            uniqExact == count(DISTINCT) == length(groupUniqArray)
- sqlancer#21 ArgExtremum              argMax / arraySort(groupArray) / groupArraySorted vs Java truth
- sqlancer#28 MaterializedColumn       MATERIALIZED/ALIAS col == defining expr (single-snapshot)

Generator/catalog:
- sqlancer#16 emit signed Int128/Int256 + Decimal256 (Decimal precision 39..76); Interval
      column emission deliberately NOT added (ClickHouse forbids storing Interval in
      tables); ClickHouseTypeParser gains an Interval read-back branch for free.
- sqlancer#23 EET roundtrip identities: unhex(hex), base64Decode(base64Encode),
      tryBase64Decode(base64Encode), toIPv4(IPv4NumToString(toUInt32)),
      toIPv6(IPv6NumToString) -- each type-gated; +7 unit-test cases.

Wired into ClickHouseOracleFactory, ClickHouseOptions (--*-oracle flags) and
.claude/run-sqlancer.sh ALL_ORACLES. mvn compile green; EETIdentitiesTest 20/20.
Probe-on-head items (recorded for dev-vm validation): query_plan_optimize_lazy_materialization,
read_in_order_use_buffering, optimize_trivial_count_query family, groupArraySorted/array text
format, IPv6 IPv4-mapped roundtrip.