Add a smoke test for DuckDB in Travis CI - #18

…ate oracles (#15,17,18,22)

Four self-contained, reader-safe oracles (every projected wire value toString-wrapped
so the client-v2 RowBinary reader never sees a raw container/Variant/AggregateFunction
column; default-on, --flag gated):
- #15 MapTupleContainer      Map/Tuple/Array extractions == Java ground truth (private fixture)
- #17 GeoMetamorphic         pointInPolygon/polygonArea/greatCircleDistance/intersection
                             metamorphic identities, integer coords, 1e-6 float tolerance
- sqlancer#18 VariantSubcolumn       Variant/Dynamic/JSON subcolumn roundtrip (toString-wrapped reads
                             only; raw-column projection emission stays gated off per plan)
- sqlancer#22 AggregateStateExpansion finalizeAggregation(arrayReduce('<agg>State',groupArray(x)))==<agg>(x)
                             for sum/min/max/uniqExact/quantileExact/groupArray + AggregatingMergeTree arm

Young-type unavailability (Variant/JSON/Dynamic/geo) tolerated to IgnoreMe. Wired into
factory/options/run-sqlancer.sh; mvn compile green. Probe-on-head: geo function names
(polygonAreaCartesian etc.), Variant subcolumn syntax (v.Int64 vs variantElement),
arrayReduce/finalizeAggregation signatures.

- sqlancer#22 AggregateStateExpansion: AggregatingMergeTree arm used finalizeAggregation(sumMerge(s))
  which double-finalizes (Code 43 ILLEGAL_TYPE_OF_ARGUMENT); sumMerge(s)/uniqExactMerge(u)
  already return the finalized scalar. Verified on head: sumMerge=10, uniqExactMerge=3.
- ClickHouseProvider: pin allow_experimental_{variant,dynamic,json}_type +
  allow_experimental_vector_similarity_index per connection so the VariantSubcolumn (sqlancer#18) and
  VectorIndexRecall (sqlancer#30) fixtures CREATE reliably (the oracle-issued SET could land on a
  different pooled connection than the CREATE). All four settings confirmed to exist on head.

Probe (head 26.6.1.743) confirmed all other 27 new-oracle constructs work as written:
Int128/Int256/Decimal(P,S), geo fns, windowFunnel/sequenceCount/retention, lagInFrame,
WITH ROLLUP/GROUPING/TOTALS, LIMIT WITH TIES/BY, *EXCEPT/APPLY/COLUMNS, SEMI/ANTI/ANY,
CoalescingMergeTree, Set/Join/joinGet, remote(), tokenbf_v1, vector_similarity, TTL DELETE,
unhex/base64/IPv4/IPv6 roundtrips.