Chez parity: STM stub + portable line-seq (janet.* audit, jolt-0obq)

Audit of the janet.*/jolt.interop/STM corpus cases vs Chez equivalents: the Janet
FFI-bridge cases (janet/string, janet/type, janet.math/sqrt, janet.string/ascii-
upper) test functionality already covered by PORTABLE corpus cases (str 29, type 9,
sqrt 3, upper-case 9), so they're safe to delete in Phase 5. Two needed a Chez
equivalent so they pass instead of being lost:

- clojure.lang.LockingTransaction/isRunning -> false (no STM on jolt).
- line-seq: the corpus case used janet/spit setup but was the SOLE line-seq
  coverage (0 other cases). Ported janet/spit->spit, and added a native Chez
  line-seq (drain a jhost io/reader + split on newline; no trailing empty line)
  that delegates a Janet map-reader to the overlay version.

zero-Janet 2694->2696, prelude floor 2648; self-host + Janet gate + JVM cert green.

jolt-cf1q.7 jolt-0obq

host/chez/host-static.ss

@@ -154,6 +154,11 @@
 (register-host-methods! "thread"
   (list (cons "getContextClassLoader" (lambda (self) (make-jhost "classloader" '())))))
 
+;; clojure.lang.LockingTransaction: jolt has no STM (no refs/dosync), so a
+;; transaction is never running. isRunning -> false (jolt-0obq).
+(register-class-statics! "LockingTransaction" (list (cons "isRunning" (lambda () #f))))
+(register-class-statics! "clojure.lang.LockingTransaction" (list (cons "isRunning" (lambda () #f))))
+
 (define (now-millis)
   (let ((t (current-time 'time-utc)))
     (+ (* 1000 (time-second t)) (quotient (time-nanosecond t) 1000000))))