Host interop fixes: ==/time/subvec/defonce + corpus cleanup

- == 1-arg returns true for any value (Clojure short-circuits before the number
  check), not 'requires numbers'.
- current-time-ms wired to now-millis so the time macro works.
- subvec truncates float/ratio indices via long (Scheme quotient rejects flonums).
- defonce checks bound? not var-get — in a top-level do the name is already an
  unbound interned cell, which var-get throws on.
- drop the line-seq corpus row (used janet/spit, N/A); allowlist char-array
  (needs Class/forName "[C").

Corpus 2678->2683, floor raised. Re-minted. Full gate green; CI green.

jolt-cf1q.7

host/chez/host-static.ss

@@ -167,6 +167,9 @@
 (define (now-millis)
   (let ((t (current-time 'time-utc)))
     (+ (* 1000 (time-second t)) (quotient (time-nanosecond t) 1000000))))
+
+;; clojure.core/current-time-ms — epoch milliseconds; backs the `time` macro.
+(def-var! "clojure.core" "current-time-ms" (lambda () (->num (now-millis))))
 (register-class-statics! "System"
   (list (cons "currentTimeMillis" (lambda () (->num (now-millis))))
         (cons "nanoTime" (lambda () (->num (* 1000000 (now-millis)))))