core: Stage 3 turn 2a — close the implicit Janet root-env leak

resolve-sym's last resort silently resolved any unknown Clojure symbol
against Janet's root environment — leaking Janet builtins with JANET
semantics into Clojure code: (type 1) was Janet's :number, (gensym) returned
Janet symbols (the long-documented (symbol (str (gensym))) macro landmine
existed BECAUSE of this), compare/slurp/int?/any? likewise. The explicit
janet/ prefix is the deliberate interop channel; the implicit fallback is
gone — an unresolved symbol is an error.

What the leak was masking, now proper interned vars:
- gensym: jolt's own (already existed, never interned) — returns real jolt
  symbols; the macro landmine is dead
- compare: full Clojure total order (nil-first, numbers, strings, keywords,
  symbols by ns/name, booleans, chars, uuid/inst, vectors by length then
  elementwise; cross-type throws)
- type: :type metadata override, deftype/record tag as symbol, else a
  taxonomy keyword (host-classified)
- int?: core-integer? — which had a latent bug the leak hid: (integer?
  ##Inf) was true (floor of inf is inf); NaN/infinities now excluded
- any?: constantly true (Clojure 1.9; SCI's namespaces.cljc needs it)
- jolt.interop/janet-type now uses the explicit (janet/type x) channel
- evaluator-test uses init (a bare make-ctx resolved EVERYTHING via the leak)

Suite 4470 -> 4532+ pass / 86-87 clean (proper compare unlocks the sort
files); baselines raised. Conformance 326x3 (+5 rows), +22 predicate spec
rows, stdlib battery green, all specs+unit. Coverage dashboard now counts
previously-leak-resolvable names honestly (missing-portable 19 -> 27).

jolt-core/clojure/core/20-coll.clj

@@ -148,6 +148,9 @@
 
 (defn keyword-identical? [a b] (= a b))
 
+;; Clojure 1.9: true for ANY argument incl. nil (used as a spec predicate).
+(defn any? [x] true)
+
 (defn comparator [pred]
   (fn [a b] (cond (pred a b) -1 (pred b a) 1 :else 0)))