core: Stage 3 — sorted collections are pure Clojure (canonical port)

sorted-map/sorted-map-by/sorted-set/sorted-set-by/sorted?/sorted-map?/
sorted-set?/subseq/rsubseq now live in their own overlay tier (25-sorted.clj).
A sorted coll is a tagged host table with a comparator-ordered :entries
vector, a 3-way :cmp, and the tier's op implementations ATTACHED to the value
(:ops map): the seed's conj/assoc/get/seq/count/... branches are each a
one-line call through (coll :ops), so the ops travel with the value — correct
across contexts, forks, and AOT images, no module-level hooks to re-wire.
The host surface grows by three minimal value primitives: jolt.host/
tagged-table, ref-put! (already there), and ref-get — a raw field read,
because plain get on a sorted coll IS the comparator lookup and reading
:entries with it recurses.

This fixes a pile of Clojure-correctness gaps the Janet kernel had:
- lookup/membership now go through the COMPARATOR: (contains? (sorted-set 1)
  1.0) was a deep= scan, (conj (sorted-set 1) 1.0) and assoc of a
  comparator-equal key now no-op/replace as in Clojure
- equality is representation-agnostic: (= (sorted-map :a 1) {:a 1}) and
  (= (sorted-set 1 2) #{1 2}) were false
- iteration was broken: (map inc (sorted-set 3 1 2)) errored
  (realize-for-iteration and coll->cells had no sorted branches)
- empty?/empty saw the host wrapper, not the collection: (empty? (sorted-map))
  was false, (empty sc) returned a bare table; it now keeps the comparator
- sorted colls canonicalize as map keys; comparator fns may be boolean
  predicates or 3-way (Clojure's fn->comparator)
- sorted-map throws on odd kv count; conj nil is a no-op

Also fixes jolt-h86 en passant: into-conj had no branch for sets (or sorted
colls) and silently returned the target unchanged — (into #{} [:a :b]) was
#{}. The fallback now folds conj. Regression rows in sets-spec.

sorted-spec grows to 77 rows (comparator-based membership, equality,
empty/rseq/printing, seq-fn interop, subseq/rsubseq on maps). Gate green:
conformance 326x3, suite 4577 (vs 4566 prior — the battery gained rows),
sorted+sets specs, full jpm test, bench at parity with main back-to-back
(4521ms vs 4619ms TOTAL under identical load).

test/spec/sets-spec.janet

@@ -9,7 +9,10 @@
   ["set? true"              "true"      "(set? #{1})"]
   ["set? false on vector"   "false"     "(set? [1])"]
   ["count dedups"           "3"         "(count (set [1 1 2 3]))"]
-  ["equality order-indep"   "true"      "(= #{1 2 3} #{3 2 1})"])
+  ["equality order-indep"   "true"      "(= #{1 2 3} #{3 2 1})"]
+  # jolt-h86: into-conj had no set branch and returned the set unchanged
+  ["into set"               "#{:a :b}"  "(into #{} [:a :b])"]
+  ["into non-empty set"     "#{1 2 3}"  "(into #{1} [2 3 2])"])
 
 (defspec "set / operations"
   ["conj adds"              "#{1 2 3}"  "(conj #{1 2} 3)"]