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).

test/integration/clojure-test-suite-test.janet

@@ -43,7 +43,7 @@
 # Raised 4004 -> 4034 / clean 66 -> 67 porting partition-all + repeatedly to the
 # overlay, which required fixing two leniencies (a char is not callable; take
 # validates its count) — correct beyond those fns, so the suite rose broadly.
-(def baseline-pass 4470)
+(def baseline-pass 4532)
 # A file is "clean" when it ran with zero failures AND zero errors.
 (def baseline-clean-files 86)
 # Per-file wall-clock budget (seconds). Normal files finish in well under 1s, so