Chez Phase 1 (increment 3b): seq tier + dynamic IFn dispatch on the Chez RT

Brings up the seq layer on the Chez runtime. host/chez/seq.ss adds one
lazy-capable node (cseq) that models Clojure's list, cons, and lazy seq -
all print as (...), all sequential-= to each other and to vectors. seq
coerces any seqable (vector/map/set/string/list/seq/nil) to a cseq or nil;
the empty seq is a distinct value printing () (rest of a 1-elem coll is ()
not nil, seq of empty is nil). Leaf ops: first/rest/next/seq/cons/list,
reverse/last, map/filter/remove/reduce/into, range/take/drop/concat/apply,
keys/vals, plus nth/peek/pop extended over seqs. map/filter/reduce apply
their fn arg through jolt-invoke, so a procedure, keyword, or collection all
work as the fn.

Dynamic IFn dispatch: a keyword/vector/coll held in a local (let binding or
fn param) and called as a fn now routes through the jolt-invoke fallback
(procedure? -> apply; keyword/coll -> lookup). The emitter only routes a
:local callee that isn't a known procedure - a named fn's self-recursion
name stays a direct call, so the fib hot path is untouched. Closes the 3
ex-known IFn divergences.

emit.janet: seq/pred ops added to native-ops with arity gates; value-position
clojure.core refs resolve to the RT procedure (native-ops names one for each),
with +/-/*// routed to flonum-coercing wrappers so higher-order arithmetic
((reduce + [])) keeps the all-double model. values.ss: cross-type sequential
=/hash so a vector and a list of the same elements are jolt= and hash alike.
rt.ss: printer learns seqs; top-level nil prints as the empty string (jolt -e
str-style). Fixed latent bug: (conj nil ...) now builds a list, not a vector.

Gates: emit-test 69/69 (fib/mandelbrot/collections/seq/IFn parity vs the jolt
oracle, fib(30) ~24ms unchanged). Subset probe 433/436 -> 595/595 compiled,
0 divergences (was 3 known), 2060/2655 out of subset. Full run-tests green
(125 files, conformance + suites included).

test/chez/run-corpus-chez.janet

@@ -28,15 +28,13 @@
     corpus))
 
 # Known subset divergences: cases that compile but need a feature beyond the
-# current increment. Dynamic IFn dispatch — a keyword/vector held in a LOCAL or
-# var then called as a fn ((let [k :a] (k m))) — is runtime dispatch on the
-# invoke mechanism, deferred to the IFn/protocol increment. The STATIC literal
-# forms ((:a m), ({:a 1} :a)) ARE supported. Allowlisted by label; the gate fails
-# only on a NEW divergence.
+# current increment. None as of inc 3b — dynamic IFn dispatch (a keyword/vector
+# held in a LOCAL then called as a fn, (let [k :a] (k m))) now routes through the
+# jolt-invoke fallback, and the seq tier closed the rest. Add a label here if a
+# future increment surfaces a case that compiles but needs deferred semantics;
+# the gate fails only on a NEW (un-allowlisted) divergence.
 (def known-divergences
-  {"param holding a keyword (IFn leftover)" true
-   "vector-in-local as fn" true
-   "keyword-in-local as fn" true})
+  {})
 
 (def ctx (d/make-ctx))
 (var compiled 0) (var pass 0) (var out-of-subset 0)