seq fns are lazy by default, like Clojure (LazySeq, not eager-headed)

map/filter/remove/take/drop/concat/take-while/drop-while/mapcat/partition
built an eager-headed cseq: the first element (and the fn application) ran
at construction, so a side-effecting (map f coll) fired f immediately and
(class (map …)) was PersistentList instead of LazySeq. This diverged from
Clojure, which wraps the whole body in lazy-seq. It went unnoticed because
the conformance gate certifies values, not realization — eager and lazy
heads produce identical values — and unit.edn even baked PersistentList in
as expected. test.check's for-all-takes-multiple-expressions (which counts
side effects in a for-all body) exposed it.

Wrap each native producer's result in a lazy-seq node so the body, incl.
the first element, defers until forced — the forced cseq still has eager
heads, so reduce/count/dorun/etc. force on walk and there's no per-element
cost. dedupe's (seq coll) is moved inside its lazy-seq. A jolt LazySeq is
now recognized by coll?/empty, the analyzer's form predicates (a macro can
build its expansion with map), value-host-tags + instance? (LazySeq/ISeq/
Sequential), and reports clojure.lang.LazySeq.

Kept the native Scheme implementations rather than porting Clojure's: a
straight lazy-seq+cons port is 3x slower and Clojure's chunked fast path is
288x slower because jolt's chunk machinery is unoptimized (filed jolt-j9dz);
the wrapped natives are Clojure-lazy at native speed.

+12 corpus rows (laziness at construction, LazySeq type, both JVM-certified).
make test + shakesmoke green, selfhost holds, 0 new divergences.

host/chez/predicates.ss

@@ -16,7 +16,7 @@
 ;; seq, (rest list), (seq coll), (map …) are seqs but not lists.
 (define (jolt-list-pred? x) (or (and (cseq? x) (cseq-list? x)) (empty-list-t? x)))
 (define (jolt-coll-pred? x)
-  (or (pvec? x) (pmap? x) (pset? x) (cseq? x) (empty-list-t? x)))
+  (or (pvec? x) (pmap? x) (pset? x) (cseq? x) (empty-list-t? x) (jolt-lazyseq? x)))
 (define (jolt-number? x) (number? x))
 (define (jolt-string? x) (string? x))
 (define (jolt-char-pred? x) (char? x))